Cat 3126 engine oil capacity

Cat 3126 engine oil capacity DEFAULT

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02-24-2013, 05:20 PM

Well the zinc and antifreeze change got completed this weekend .I found parts of an impeller in the heat exchanger when I pulled the endcap off looking for a broken zinc on our port 3126 Cat.The engine has never run anywhere near hot but before we leave for Bioloxi I plan on checking both engine impellers.This will be my first oil change on these engines and next on the list.I checked with the Cat folks here in Mobile and they are telling me that I should use only one oil.40 wt Cat pn 170-5261 because these engines have mechanical unit injection(what ever that is).Its pricy and each engine holds 6.6 gals.This is the first time also that I've seen the maint manual to say to install the filters dry shut the fuel off and spin the engine over for 30 secounds.I'm looking for a cheeper alternative for the Cat oil.They specify it as CF CF-4 CE4 and SJ.Any one know another oil that will meet these specs and what they mean?I think they quoted this oil at $21 per gallon.Are they blowing smoke or are you guys paying near that?I think I'll stay with the Cat Filters.


02-24-2013, 07:32 PM

Cat oil is Mobil. Any CJ4 (that's the new designation) will be fine. They all have to meet the same ASTM specs.

We run a bunch of Cat equipment and we have always used Mobil Delvac. No problems and most engines go 20,000hrs+ before overhaul.

jim rosenthal

02-24-2013, 07:58 PM

Cat devised this oil for 3116 and 3126 engines because of ash problems with regular diesel oils. It IS made by Mobil, but they made this oil up for Cat and deleted some additives that were causing problems. I think they call it Cat SAEO or something like that? If memory serves, it is 30 weight oil.

The fact that their engines needed a special oil with deletes underscores the problems they had with all these engines. Yours are old, I assume- they haven't been made in a long time, fortunately. Look on the forum and post a question about this; you'll get some answers which are likely to be helpful. Given the amount of trouble these engines can cause you, I'd stick to Cat's oil unless you can get very clear information that another less expensive oil will not cause ash problems inside the engine. Good luck.


02-24-2013, 09:12 PM

Cat devised this oil for 3116 and 3126 engines because of ash problems with regular diesel oils. It IS made by Mobil, but they made this oil up for Cat and deleted some additives that were causing problems. I think they call it Cat SAEO or something like that? If memory serves, it is 30 weight oil.

The fact that their engines needed a special oil with deletes underscores the problems they had with all these engines. Yours are old, I assume- they haven't been made in a long time, fortunately. Look on the forum and post a question about this; you'll get some answers which are likely to be helpful. Given the amount of trouble these engines can cause you, I'd stick to Cat's oil unless you can get very clear information that another less expensive oil will not cause ash problems inside the engine. Good luck.Wellwe are not that cheensey.Just seems to be a large $ amount for a gallon of oil.


02-24-2013, 09:20 PM

Cat makes a 30# oil for the 3126. They found that additives in the multi weight oil were fouling the aftercooler, so Cat designed a special oil without them.


02-24-2013, 09:22 PM

This may answer your questions. It's a cut-n-paste from the Sea Ray site. Looks like maybe the Cat oil is part synthetic which would explain the price.

Caterpillar specifies either SAEO 30 or 40 or a single viscosity or a single viscosity CF-4 commercial oil. SAEO is "special application engine oil" which is a synthetic developed by Caterpillar and is formulated to minimize oil deposits in the aftercoolers on 3116/3126 engines. SAEO is very expensive and is only available from Cat dealers near the water since the oil isn't recommended for applications other than 3116/3126 marine engines.

Select your viscosity based on this table:

Lubricant Viscosities for Ambient Temperatures
Ambient Temperature
Viscosity Grade
Minimum Maximum
SAE 30 0 °C (32 °F) 40 °C (104 °F)
SAE 40 5 °C (41 °F) 50 °C (122 °F)

Cat DEO SAE 30 /40 has limited application and can be hard to find. Most Cat owners use either Rotella T SAE 30 or 40 or DELO 400 SAE 30/40 because they are commonly available.

The key is to use a single viscosity SAE oil with a CF-4 API rating with no viscosity enhancers.

Its long, but you might find Caterpillar publication SEBU6251-12 interesting if you want to wade thru it.

jim rosenthal

02-25-2013, 09:50 AM

I'm sure it IS expensive; it was only available from Cat Marine dealers since it was only used in those marine engines. I've got some sitting around, or had some; I don't know where you are, but you can have it for free for shipping it to you. When I get home tomorrow I will see how much I have. You are welcome to all of it. PM me with your location.


02-25-2013, 08:19 PM

I'm sure it IS expensive; it was only available from Cat Marine dealers since it was only used in those marine engines. I've got some sitting around, or had some; I don't know where you are, but you can have it for free for shipping it to you. When I get home tomorrow I will see how much I have. You are welcome to all of it. PM me with your location.1620 Erdman Av Mobile al 36618 2516102611 and we would appericate it and we will help with the freight.Very nice of you---


02-26-2013, 07:04 AM

Oil is getting expensive, any oil.

These days the best i can find down here on rotella 15w40 is $79 for a 5 gal pail or about $16 a gallon (went thru 45 gallons of it yesterday doing a change on the 3412Es in the boat I run) $21 a gallon for a dealer supplied specific oil isn't bad. Is that for gallons or pail? Pail should be cheaper

I always install the secondaries dry, it's to avoid contamination. Many engines have a priming hand pump that reduce the amount of cranking needed, check yours

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CAT C7 Specs and Engine History

CAT C7 EngineAt the turn of the century there was a lot of buzz around a new diesel engine being produced at Caterpillar, one that could meet the growing emissions requirements enacted by the EPA. The Caterpillar C7 Engine was supposed to be the “golden child” in Caterpillar diesel engine lineup; one that combined raw horsepower with computer controlled clean emissions. However, sometimes things don’t go according to plan. The engine was produced from 2003 to 2009 and was installed primarily in over the road medium duty class 8 trucks. All of the big players in the trucking industry hopped on board hoping the CAT C7 was going to live up to the hype. Paccar, Freightliner, Ford and GMC all purchased the engine in droves. The technical classification of a medium duty tuck is a single drive axel with a gross vehicle weight of 18,000-33,000 lbs.; mostly box tucks, tow trucks, daycabs, and straight trucks.

The Caterpillar C7 was designed mostly out of necessity vs. practicality. Caterpillar, needed to produce a new engine that was going to meet or exceed the Tier Ratings enacted by the EPA in 1994 to curb diesel engine emissions. The stricter Tier 4 emissions requirements went into effect January 1, 2004. The Caterpillar C7 was released in 2003, only months ahead of the Tier 4 ratings change, and replaced the popular 3126 model. Older CAT engines like the 3116 or 3126 were essentially grandfathered into the older tier rating requirements and did not need to be upgraded.

CAT C7 Commonalities With CAT 3126

The CAT C7 shares many common configurations with the CAT 3126. The engine configuration was the same as the 3126 but the fuel system changed using a new engineered style known as the HEUI injector. The HEUI injector allows for multiple injections at different metered rates. Using a staged fuel distribution ratio helps improve engine combustion which ultimately reduces emissions ouput. The electronic configuration was also more robust to offer better fuel management and electronic sensors into the engine. The CAT C7 was really the first heavy duty diesel engine to offer a greatly expanded ECM or electronic computer module. The ECM is the same hardware as previous electronic engine generations just upgraded to handle more systems. Using an advanced 120 pin connection the amount of CAT C7 ECMinformation the computer was able to process was astronomical. Other similarities between the CAT 3126 and CAT C7 include the same bore and stroke at 4.330 and 5.000 respectively. The cylinder heads are slightly different in the common rail design, still 3 valves per cylinder but there is no oil rail cast in the CAT C7 cylinder head.

The most noticeable difference between the CAT 3126 and CAT C7 is within the valve train. The front gear train is mostly the same except for the gears which have fewer teeth and a more robust design. Some speculate that the reason for the wider gear teeth is so that the gear designs can’t be interchanged with older CAT 3126 and CAT 3116 versions. The oil pump and water pump are also larger to accommodate the need to lubricate/cool more moving parts.

When examining the crankshaft and rods the common differences between the CAT 3126 and the CAT C7 include smaller crankshaft counterweights to include the lighter weight piston design. The connecting rods and crankshaft share the same journal sizes but are slight different in terms of cast size and shape. The connecting rods in the Caterpillar C7 ACERT are not forged, liked the CAT 3126, but consist of powdered metal with a fractured cap design. There are also various sizes and configuration of the connecting rods depending on the piston used in the engine.

Horsepower is the determining factor when choosing the piston configuration in the CAT C7. The two options include a taller aluminum piston with a 1.811 wrist pin for 230 hp and higher versions and a shorter 1.52 diameter one piece steel piston for engine configurations below 210 hp.

CAT C7 ACERT Technology

CAT C7 Injection SystemThe CAT C7 includes the ACERT technology which is an air/fuel management system to control NOx emissions regulations. ACERT stands for “Advanced Combustion Emissions Reduction Technology”. Highlights of the ACERT technology include a closed crankcase breather and diesel particulate filter using CAT’s engineered regeneration technology. With the upgraded ECM the technology allows for a more precise control over the combustion cycle by monitoring the incoming air and fuel as well as the exhaust after treatment.

With the ACERT design the smaller CAT C7 models used an air inlet system with multiple traditional wastegated turbos to boost air intake flow and pressure. The more midsized hp models used only a single turbo while the larger horsepower models used dual turbochargers working in conjunction for optimal airflow. Within the design of the C7, the turbos use variable geometry valve actuation controlled by the ECM to adjust the perfect amount of airflow into the combustion chamber. This variable valve actuation also allows for the CAT C7 to offer an integral jake brake on two of the heavy duty diesel horsepower models.

The fuel delivery system on the CAT C7 is hydraulic electronically controlled unit injectors for the mid horsepower models and mechanically actuated and electronically controlled on the higher horsepower models. Both systems are metered and timed to inject multiple bursts of fuel to create a more efficient combustion cycle.

Lastly, the ACERT technology offers an exhaust after-treatment. The after-treatment technology reduces NOx particulate matter in the muffler via a spray of an oxidation catalyst agent. The after-treatment function is fairly straightforward and requires no additional cleaning or maintenance. Later ACERT technology on the CAT C13 and CAT C15 incorporated more advanced Selective Catalytic Reduction (SCR) technology, Exhaust Gas Recirculation (EGR), Diesel Exhaust Fluid and more robust Diesel Particulate Filters.

CAT C7 ACERT Problems

Diesel Particulate Filter DiagramWith diesel engine technology there are two rating systems to determine the average life expectancy of the engine: B10 and B50. B10 is the average life expectancy of an engine measured in miles where 10% of the produced engines failed and needed a major overhaul. Consequently, B50 is the average miles where 50% of the engines failed. With the CAT C7 the B50 rating of 450,000-500,000 miles. This means half of the CAT C7 engines had a major engine failure at 500,000 miles and needed an overhaul. According to the B Rating System an “overhaul” or “major engine repair” is regarded as removal of the cylinder heads and/or dropping the oil pan with an inframe repair. Failures or parts replacement without removing the cylinder heads or dropping the oil pan are not counted in the B10 and B50 engine life statistics. This failure rate for the C7 isn’t terrible in relation to other diesel engines. For example the B50 rating for the popular Cummins 5.9 engine is only 350,000 miles. However, a Detroit Diesel 60 Series can easily go 1,000,000 miles before overhaul.

The ACERT Technology had a lot of problems for Caterpillar, first with the CAT C7 but more so later on with the CAT 13 and CAT 15 engines. The technology was really the first generation emissions technology for heavy duty diesel engines. The ACERT technology was prone to numerous regeneration issues. Drivers reported low power and low fuel economy. It was common that the CAT C7 ACERT engines would experience overheating when driving up an incline. The cooling fan does not kick in until 235 degrees Fahrenheit while many drivers reported overheating at 200 degrees Fahrenheit. The engines run hotter to burn off more diesel particulate matter. Drivers are instructed to downshift to 1100 rpm when going up an incline to avoid overheating. Other issues regarding the CAT C7 ACERT technology is clogged diesel particulate filters as well as clogging of the inlet of the turbocharger. The ACERT technology was not well regarded due to its numerous issues with maintenance, fuel economy, and lowered horsepower. The company stopped producing over-the-road engines at the end of 2009 and elected not to meet the stricter 2010 emissions requirements by the EPA.

The original Caterpillar C7 would change configurations once again in 2007 to adjust to changing market demands. In 2007 diesel fuel itself changed to Ultra Low Sulfur Diesel or ULSD. The fuel change dictated that the fuel system of the CAT C7 ACERT needed to change to a common-rail injection system. The new common-rail injectors took injection pressures to 25,000-27,500 psi. The fuel transfer pump supplies the fuel to the fuel rail at 280 psi. Overall, the common rail system worked well but added another system or point of failure within the CAT C7 Engine.

Ultra Low Sulfur Diesel is thinner which means the fluid is vicious. Since the lubricity is lower this equates to better fuel circulation at a high pressure to keep the heat levels down. In the later 2007 models the turbocharger was also upgraded to variable nozzle technology which can offer appropriate boosts of horsepower at all engine rpms.

C7 Dimensions and Operating Capabilities

CAT C7 In Semi TruckThe Caterpillar C7 engine is an line 6 cylinder diesel fueled engine with a displacement of 7.2 liters. The maximum heavy duty hp dry weight is 1,425 lbs., with an oil capacity of 4.75 gallons or 6.75 gallons with the deeper sump pump and oil pan. The cooling system and water pump allow up to 3.99 gallons. The CAT C7 was available in 8 different horsepower ratings from 210 hp – 360 hp with torque ratings from 520-925 lb-ft of torque. The 330 hp and 360 hp models were only available in recreation vehicles and firefighting equipment. The first Caterpillar C7 models (210, 230 and 250 hp) were available in both low or high torque options. The torque options allowed for different transmission applications preferred by the various big truck manufacturers. Each manufacturer’s torque capacity was different and had to be matched with the CAT C7 of choice.

Overall the CAT C7 ACERT Engine represents the beginning of the end for Caterpillar’s long rein with over-the-road diesel engines. The company ultimately didn’t feel the cost of continuously producing emissions upgrades was worth the time and effort and exited the over the road industry in 2010 paving the way for Cummins and Paccar. Caterpillar still makes a great engine and continues to produce off-road construction equipment effected less by strict emissions regulations.

CAT C7 Engine Specs and Technical Data

Engine SpecEngine Data
Minimum Power225 hp, 520 lbs-ft torque
Maximum Power300 hp, 925 lbs-ft torque
RPMs1800-2200 RPMs
Emissions RatingsU.S. EPA Tier 3 Equivalent, China Stage II, EU Stage IIIA Equivalent
Engine ConfigurationInline 6, 4-Stroke-Cycle Diesel
Bore4.33 in
Stroke5.0 in
Displacement7.2 L
AspirationTurbocharged Aftercooled
Compression Ratio16.2:1
Combustion SystemDirect Injection
RotationCounter Clockwise
Fuel SystemHEUI Injection, ACERT Technology
Computer SystemADEM A4 Electronic Control Unit
Dry Weight1296 lbs.
Height40.6 in
Length41.5 in
Width29.8 in

Remanufactured CAT C7 Engines

Considering the CAT C7 is prone maintenance is overhaul issues it is an engine we rebuild quite frequently here at Capital Reman. We offer two options when it comes to remanufactured CAT C7 ACERT and Non ACERT Engines:


CAT C7 Longblock EngineWe can remanufactured a brand new CAT C7 Engine on an exchange basis meaning we build a new engine from a core. When we deliver your brand new engine you simply send us your old core back. We have a very fair core return policy. If the camshaft, crankshaft, cylinder head and block are reusable we will return 100% of your core charge. If some of the internal components are worn beyond repair we will pro rate your return.

Our Longblock CAT C7 Engines include the cylinder block, complete cylinder head, crankshaft, pistons, liners, rings, connecting rods, camshaft, followers/lifters, intermediate cover, front gear timed group and complete gasket sets. Turbos, injectors, oil pumps and water pumps can also be ordered with the engine.

Repair & Return:

Repair and Return engines will follow the same procedure as remanufactured exchange engines however Capital Reman Exchange will rebuild the components provided by the customer. From time to time there are components that can not be remanufactured with the customer's engine. In instances where parts can't be remanufactured the cost of replacement parts or components will become the responsibility of the customer if they elect to replace them. There is no core charge associated with Repair & Return Engines.

- Save 47% On Average Over DealersCAT C7 ACERT Engine- Get Back To Work Quickly - We Don't Believe In Wasting Your Time- 88 Point Engine Quality Control Checklist- Built to Exact Manufacturer OEM Specs- Built With All ISO 9001 Certified New Parts- Industry Leading 1 Year Unlimited Warranty- Over 80 Years of Combined Engine Building Experience- AERA Certified Machine Shop and Engine Rebuild Facility- Fair Core Refund Policy- Worldwide Shipping- Same Day Shipping on Parts- Full Service Machine Shop and Engine Rebuild Facility-Manufactured In-House in Denver, CO

Call Capital Reman Exchange Today at 1-844-239-8101 For Immediate Caterpillar C7 Engine and Pats Sales or Service or Read Our FAQ Page to Learn More.

Tags for this article
CAT C7, CAT C7 ACERT, Caterpillar, Diesel Engine Remanufacturing, Diesel Engines, EPA Emissions Technology, Remanufactured Diesel Engine

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'I am a fairly new owner (8 months) and have not down that yet. I presume you are an experienced tinker if not mechanic, or would not be considering this. 
From my viewpoint the biggest difference I expect to find, as compared to working on a light duty diesel as found in passengers cars, will be the size of your oil drain catch bucket. I have “heard” oil capacities for this engine ranging from 22 to 32 quarts depending on whether you have a shallow or deep pan. Prepare to catch 32 plus quarts. That is a challenge there. 
Obviously you do not have your chassis manual which states filters and capacities.  I expect that information has been posted on this forum.  Capacity wise, if nothing else, determine where are fill wise by dipstick before you drop, measure all your drainage including the filter, and start there as a refill point. 
Filter wise, from potential susceptibility of our High pressure unitary injection pump to fail from dirty oil ingestion, I am looking for the best oil filter I can, I presently “presume” that should be the Caterpillar “ high efficiency” series filters. A dealer or reputable reseller should tell you what that is with the model number and serial number off your engines ID plate (located on the valve cover). 
I hear Caterpillar does not recommend priming oil or fuel filters for fear of contaminants being introduced?  If you do.not prime your oil filter, certainly do not touch your throttle on the first start after a servicing till you register normal oil pressure. There is An Adept Ape series on Youtube regarding Caterpillar engines I follow. 
You can grab filter numbers off the presently installed filters for starting pints. This presumes the last person installed the correct filters, verses a convenient filter the shop had on hand. 
From the prices I have heard people pay for replacement radiators, I would stay on top coolant maintenance.  Large diesels take a slightly different product from automotive products. I would use the OEM product here too as CAT’s coolant is an extended life product with less work/worry down the road. 
Engine oil: not even going to start a debate on that.  CAT requires oil change intervals based on sulfur content of our fuels.  Now that this country is on extra low sulfur fuels, we take the longest change interval which is something beyond 5,000 miles.  Oil should at least be the latest API standard for Diesel engines, usually 10-40 weight unless you are in very cold climates or like synthetics.  I do not see where CAT has required synthetics for our engines, or even gives you credit for such in the service intervals. If you want to drill down on this, their are CAT specific forums on other RV forums sites.  Once a year is the maximum time intervals for all filters.  Once you know what the correct fuel filters are, keep a spare of both on board with tools to change them.  
Regarding you chassis grease fittings, my Magnum owner’s manual outlines their locations, as well as filter numbers.  I would inspect every moving suspension linkage including the king pins for a grease fitting.  Note there is one non-chassis fitting we do not want to overlook.   It is reportedly on an idler bearing on one of our two drive belts. 
Our Allison 3060M transmissions are well built reliable units.  They spec using their proprietary full synthetic fluid trademarked Transend.  The service interval is something like 100K or better. I would certainly have mine serviced regardless of mileage if it has not been done in the past twenty years. It has two large cartridge filters and possibly a pan filter.  These parts will not be priced like your father’s Oldsmobile parts. 
Another service item I feel is important on a bi-annual basis (my schedule) is replacement and flushing of brake fluid on our hydraulic brake system.  
I have not seen an interval on the ATF based hydraulic fluid which drives our power steering and brake booster.  I would at least change it if it ever darkens in color (is normally red), the reservoir is in our “service compartment area”. Keep a good eye on all hoses with them hitting the twenty year mark.  
 I expect others with real experience and knowledge of where the FAQ type subjects will respond. 
Taylor Hudson‘98 Serengeti (4060), CAT 3126 of ‘97 vintage

On Thu, Jun 13, 2019 at 3:14 PM [email protected] [Safarifriends] wrote:

Hi again,
I want to do the oil change myself for the first time and I was wondering the usual questions: how much, what type, other things to change (filters, etc). My question is so basic I am surprised to not find anything on safarifriends, someone for sure has asked the question in the past but I cannot find it.

So, to begin, in order to determine the oil capacity, I suppose I have to know what kind of engine model I have, I know it's a CAT 3126 but how to know if it's a B or an E? 

What type of oil should I use? Something designed specifically for the CAT? 

How to know if the different filters have also to be changed or not? 

For the zerks greasing, I found a Magnum manual with the lubrication diagrams but I don't know what kind of chassis I have, is it a Blue-Streak, a Blue-Max, etc?

Something else important that I should include in my maintenance routine? 

If someone could point me towards something like a 1-pager that adresses these questions, I would be very glad!

Thanks again,
Sahara 96, CAT 3126, Magnum chassis

DIY Diesel Fuel Filter change on Caterpillar 3126 engines on Calypso II

How much oil is enough?

Topic URL:
Printed on: 10/22/2021


Topic author: Gary Osburn
Subject: How much oil is enough?
Posted on: 08/19/2006 06:52:54 AM

The Caterpillar book that came with my 2001.5 D with the 3126B clearly states that it requires 22 quarts if it has the shallower oil pan and more if a deeper pan. I have the shallow pan and have been to a couple of Caterpillar seminars at rallys. Always the recommendation was for 22 quarts. (At one seminar, a Fleetwood representative said the all Discovery motorhomes came with the shallow pan.)

Early this week at the new Oasis Freightliner service center at Gaffney, I was told that Caterpillar had changed their mind and that the proper fill is now 19 quarts. Also that the extra 3 quarts finds its way out the vent slobber tube into the charge air cooler and radiator and all over the towed car. No wonder we have all had so much trouble with this. Maybe 19 quart fills would help.

Gaffney seems to me to be a pretty good authority on this but has anyone got anything from Caterpillar on it? Especially anything in writing?

Also, I just had to clean mine again (before I went to Gaffney). I had extended the slobber tube four years ago and was getting a slight overheat in the past few weeks. I took up the closet floor last week and it looked like the fan, charge air cooler and everything nearby were coated with asphalt. I cleaned it this time with air conditioner condenser cleaner in a pump sprayer and rinsed with lots of water. What a difference - I don't have to limit speed on every little hill according to the temperature gauge anymore!



Reply author: jrpainter
Replied on: 08/19/2006 10:38:06 AM

Gary, My experience and most of the current CAT documents apply to the C7 not the 3126. It's well documented that the 19 qts is correct for a C7 shallow pan, but I'm not sure if it applies to any 3126. I found this reply from Tad Petri, the CAT rep who monitors the Yahoo CAT RV owners group forum.


Call their RV help center with your engine serial number to confirm if its appropriate for 19 qts. CAT's first suggestion to everyone who complains about excessive oil blowby, is to verify the oil level. This also requires verifying your oil dip stick calibration. When CAT lowered the oil capacity for their engines, Freightliner didn't always get the right dip stick installed. If you rely on an inaccurate dip stick, you may be over filling the oil.


Reply author: BCapers
Replied on: 08/19/2006 10:51:00 AM

This has been a much discussed topic every since the newer "C" family of CAT engines have made their appearance.
I have the 3126E engine in our 2002 37T, and the information that came with it called for 22 quarts of oil, which I have been using since day one.
Doing some research, I found that the earlier 3126 engines called for 19 quarts, and an oil change interval of every 9,000 miles or 1 year.
In order to keep up, so to speak, with Cummins, CAT increased the oil level to 22 quarts, and extended the change interval to 11,000 miles/1 year.
When CAT went to the newer "C" class engines, they revamped the valve cover, and lowered the vent which caused an excessive blowby when using 22 quarts of oil. The solution was to lower the oil level back to 19 quarts in those engines, but keep the 11,000 mile/1 year change interval.
My CAT RV Recommendations sheet �1999 specifies 22 quarts for the 3126 engine. The newer version of the same document which now includes both the 3126 and the "C" class engines state 19 quarts.
So, I guess it is a crap shoot, as to what quantity of oil you use in your 3126 engine. My dipstick is calibrated for 22 quarts, and I have continued to use this amount of oil with no adverse effects, and practically no oil consumption or blow by problems between changes.
If you are having a serious blow by problem with your 3126, you could, per CAT, drop the oil level to 19 quarts and still be within their specifications, however if you do this, the oil level on your dipstick will be at the "ADD" mark when full, so you might need to have it recalibrated.
I feel more comfortable in having the 22 quarts of oil over the 19 quarts, and will continue to run that level.
I don't think your radiator being covered with asphalt has anything to do with the oil level you are running.

2002 3126E 330 CAT

Reply author: Larry
Replied on: 08/21/2006 10:33:29 AM

Regardless of which engine you have the capacity is determined by the depth of the oil pan. It's easy to tell the difference, the 22 qt. pan is much deeper. I have the 3126B and it has the 18 qt. pan.

The only safe way is to change the oil and filter. Fill with 18 qts.(plus one qt. for filling filter) or 22 qt.(plus filter) if you have the deep pan. and run engine for a couple minutes. Shut the engine off and let stand, on level ground, for at least 30 minutes. Then check the dipstick, this level is where your full mark should be. As in all things, it's not foolproof, but it's as close as we can get.

Reply author: BCapers
Replied on: 08/21/2006 12:05:50 PM

According to my 3126 CAT Operation and Maintenance Manual;
Page 142, Table 19, Under the heading of 3126B and 3126E Truck Engine Approximate Refill Capacities; the Shallow Oil Sump is 22 quarts, and the Deep Oil Sump is 30 quarts.
On Page 143, Illustration 18 shows the outline of both the Shallow (22 quart) and Deep (30 quart) oil sumps. The shallow sump has smooth sides, and the deep sump has fluted sides.
One look at the illustration makes it clear which is the shallow one, and which is the deep one.
Actually for my shallow pan (22 quart) the correct amount of oil is 20 quarts, and the filled oil filter holds an additional 2 quarts for a total of 22 quarts.
Per printed instructions from CAT, the instructions I got for calibrating the dipstick for the 22 quart system is as follows: Level the vehicle with a warm engine, and Drain oil, and remove old filter, and replace filter with a new dry one.
Install 17 quarts of oil in the pan. Mark the dipstick as this being the ADD point. Intall an additional 3 quarts of oil, and mark the dipstick at the FULL point. Start engine and run for 3 minutes, then turn off engine, and allow it to sit for 30 minutes. Add additional oil to reach the FULL mark on the dipstick, (normally 2 quarts which filled the filter).
The manual for your 3126B may state otherwise, however this is what mine states.
I guess the bottom line is for each and every one of us to read and follow the manuals that we got with our rigs, for what might be right for my 3126E may not be right for your 3126B, and neither might not be right for the newer "C" class engines.

2002 3126E

Reply author: Gary Osburn
Replied on: 08/21/2006 5:37:25 PM


Oops, Sorry, somehow I hit a wrong key and posted half a message.

Reply author: Gary Osburn
Replied on: 08/21/2006 5:56:39 PM

Interesting. Mine is the 1326B and I have the same book as Bill, with the same pictures. Since it's the smooth-sided pan, I assigned it the 22 quart size. This was verified, at least in my mind, by the Freightliner Rep I mentioned earlier. This was at the Caterpillar Engine seminar at the Great North America Rally in Hutchinson in 2004.

I've changed the oil myself a couple of times and poured the old oil back into the jugs for return to a re-cycle center. It never comes up to the 22 quarts I'm putting in. Those extra quarts (seems to be about two) are probably not getting burned up but are blown out and getting on the fan blades, into the CAC, and all over the towed car.

I'm thinking of cutting back next time, maybe to 20 quarts; just too chicken to go against the book, have an engine burn out from low oil, and Caterpillar tell me it was all my fault. Thought maybe somebody had seem something in writing from Caterpillar.

After that cleaning, I was sure running cool and zooming up those I-40 hills heading west from Charlotte last week. I'll give my radiator cleaning job a real test in the next few weeks around Yellowstone and the Grand Tetons.


Reply author: godwinm
Replied on: 08/21/2006 6:51:01 PM

For the 3126/3126B/3126E/C7 Cat engine with shallow oil pan the recommended capacity is 19 quarts as per this document on the Cat website below

Marshall G.

Reply author: Larry
Replied on: 08/23/2006 3:25:40 PM

My book does list 22 QT for the shallow and 34 QT for the deep pan. But this is "capacity for rebuild initial fill". Next to these figures are the standard 19 QT and 30 QT(are there three sizes of pans?). I was told the deep pan is normally used on off-road engines.

It's a problem knowing what is correct as CAT publishes a couple different figures. The Freightliner book lists 19 and 22 QT pans. Serial #s prefix 1WM and 7AS have 19 QT, serial #s 7AS, 8YL, 9SZ and CKM have 22 QT. Note that 7AS is listed on both. This is just what Freightliner lists in their maintenance guide

Reply author: BCapers
Replied on: 08/23/2006 4:16:59 PM

The problem seems to be that Caterpillar cannot seem to make up its mind as to how much oil should be used in their engines.
As I have mentioned above, for my 3126E (CKM) engine with a shallow pan, the CAT Operators manual states 22 quarts.
In 2002 I went to a Cat Engine Seminar, and the following information was given in a handout:
Serial # 1WM & 7AS Shallow Pan = 19 qts 9,000 Miles/ 1 Year
Serial # 7AS*, 8YL, 9SZ, CKM Shallow Pan = 22 qts 11,000 Miles/1 Year
The 7AS* indicates a recalibrated dip stick, and three additional qts of oil which extends change interval from 9K to 11K miles/ 1 year.
In 2004 I went to another CAT Preventive Maintenance Seminar, and the information published by CAT at this one states that the 3208/ 3126/3126B engines for the shallow pan require 22 qts/ 1 year between oil changes.
Caterpillar's Document LEHT9288-01 (10-99) states that for the 3126/3126B shallow pan, 22 quarts of oil are required.
Caterpillar's Document LEHT9288-03 (8-04) states that for the 3126/3126B/3126E/C7 engines with a shallow pan, 22 quarts of oil are required.
Caterpillar's Document LEHT9288-04 (Dated 2005 if memory serves me right) as posted on their web site, lowers the oil level for the 3126 series and C-7 engines with a shallow pan back to 19 quarts.
From the documents I have quoted, all 3126 engines with the 11,000 mile/ 1 year change interval called for 22 quarts of oil.
When the C-7 engine came on line, the valve cover breather port was changed, and thus 22 quarts of oil would result in excessive blowby out the vent tube, so rather than change the valve covers to the older sytle, they simply lowered the oil level to help eliminate the blow by.
I myself have used 22 quarts in my 3126E from the beginning, and will continue to do so, since I don't have a blowby problems.
I guess, per the latest publications I could drop the level to 19 quarts, recalibrate the dipsitck, and be within CAT's latest specifications, however I feel more comfortable running the 22 quarts in my engine.

2002 3126E CKM engine.

Reply author: Larry
Replied on: 08/23/2006 6:55:58 PM

Good information Bill, well done.

Do you think it's a possibility that the shallow pan was enlarged? I've found several references to a 30QT. pan, also 19 and 22QT. Or do they just run the 22qt. pan three quarts low to avoid blow-out?

Reply author: drmutziger
Replied on: 09/12/2006 08:57:39 AM

I have a 2003 with a 3126 330 cat engine. I spoke to the factory rep and was told that 19 quarts was the correct amount of oil inspite of the fact that the spec did call for 22 quarts. The factory rep indicated that by using the 19 quarts two things will occur, first less blow back and second improved circulation due to less flinging of oil in the pan causing capulation effects.


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Oil capacity cat 3126 engine

NE part of SW Iowa

I believe that there is 3 different oil pans, for those engines. (steel pan verses alum. oil pan and their depths are different, too) 

I know the motorhome oil pans are different, also. (and their Operation and Maintenance manuals were writting incorrectly, too= they stated/printed a completely empty engine, where they should have stated/printed the "oil change amount" because almost 3 quarts of oil are trapped in the HEUI system{between the HEUI pump, HEUI oil rail, Injectors and probably some in the main oil gallery, too}) Note: This caused a lot of motorhomes to be Overfull of oil, and thus, oil came out the blowby tube.  

Maybe Bern will chime in, He has access to CAT's System for Operation and Maintenance manuals(Refill Capacities). He will need to know your serial number prefix and depth of oil pan(measure distance between engine block to bottom on the oil pan)   

Edit: Went to find my old invoice, for CAT oil, and remembered that I had them print these out, for me. This is for a 2002 Frtlnr FL70 w/ 3126 engine "CKM" serial number prefix.

Edited by 4WD 12/21/2012 21:29

(2002 CAT 3126 oil refill chart 002.jpg)

(2002 CAT 3126 oil refill chart 003.jpg)

Attachments2002 CAT 3126 oil refill chart 002.jpg (29KB - 840 downloads)
Attachments2002 CAT 3126 oil refill chart 003.jpg (35KB - 756 downloads)
How To Perform A Professional Cat Diesel Engine Service. Cat Engine Oil Change.


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