Cat C12 Oil Capacity, Type, and Change Interval (Guide)

To keep this powerful engine running on all cylinders means you have to look after it on a regular basis. Changing the oil is not enough. You need to make sure that you use the right type of oil as well as the right amount. That way every part that needs lubrication is lubricated correctly.

The oil capacity for the C12 engine is 9.4 gallons or 36 liters. The type of oil you should use would be 15W40 and it should be ci-4 or cj-4 rated. The brand won’t matter that much.

To learn more about this topic, just continue to read our article. It has the information you want to know about if you own a C-12 Caterpillar engine. Take a few minutes to get this important information so you can take care of the motor the right way.

How Much Oil Does a Cat C12 Hold?


These are rather large motors that reach 12L or 732 cubic inches in size. They can produce up to 445 HP at 1600 rpm and go for about 600,000 miles before any severe maintenance needs to be done to them.

What helps these motors reach those accomplishments is the 36 liters of oil in the crankcase. The 36 liters translates into 9.4 gallons so you will be buying a lot of oil at oil change time. Be prepared to store some extra oil.

That 9.4-gallon amount is just over 3 times the amount of coolant you need to keep this engine from overheating. The coolant system needs 2.7 gallons or 10.2 liters of antifreeze.

Both liquids are needed to keep this 2070-pound engine running on all 6 cylinders. The engine is an inline 6 and its top engine speed is 2100 RPM. You will want to look after this engine.

Its major problems do not usually occur until around the 600,000 to 700,000-mile mark which means you get a lot of worry-free driving especially when you do not put a lot of mileage on your vehicle.

Cat C12 Oil Capacity


The oil capacity is as we have already said, 9.4 gallons of oil. That is going to mean that you will have some oil left over after your oil change. About 6/10ths of a gallon to be exact which you may be able to use in other diesel-powered devices like generators, etc.

To have this engine last as long time regular oil changes and other maintenance helps keep this reliable motor running like a finely tuned watch for a very long time.

Even if you do have problems early on, the cylinder liners inside the engine make this motor rebuildable. That means you can solve the problem and have it running for a very long time after a major overhaul.

The longevity of this motor is well known. Some have been known to make it to 1,000,000 miles before needing any major work done to them. But when you get to those higher mileage marks watch out for coolant leaking into the oil, head gasket failures, and lifter and cam repairs.

The water pump may also go out on you. This part can start to leak on you when it gets older.

Cat C12 Oil Type


In most cases, the oil brand does not matter. But you should be wary of those no-name brands that offer oil at very attractive and affordable prices. If you are going to buy oil for this engine spend a little more and buy the more well-known brands of oil.

That way your engine receives the best protection and can last longer. This may be a little more expensive but using 15W40 oil from a top brand is the best way to go.

However, before you buy the oil, make sure the type you buy is made for diesel engines. It should say clearly on the front label diesel engine oil. If it doesn’t, then move to another brand.

What CAT warns people about is buying what may seem to be CAT products from third-party vendors. You may be buying counterfeit CAT products and not the real thing.

These counterfeits look good and almost like the real deal but their quality level is often very low. When you put them in your engine, you may be putting the motor at risk for damage.

Cat C12 Oil Change Intervals


According to a CAT data sheet, you should be changing the oil once a year or every 15,000 miles. 

This sheet is designed to help RV owners when their RV has the C-12 under the hood. Besides being able to use 15W40 oil this sheet says that 10W30 type oil is also okay to use.

Then you should do your initial valve adjustment between 15,000 and 60,000 miles for peak performance. The next valve adjustment should be done at the 240,000-mile mark.

The data sheet provides a lot of pertinent maintenance information that would be wise to make a note of so you can help your engine last a very long time. Just be careful when you ask these types of questions on RV discussion forums.

You may get a lot of information that is not helpful to you. Look for the data sheets from the company to get the right information.

Some Final Words

These engines hold a lot of oil but they are big. They need the extra oil so that they can perform their duty without breaking down. With the right oil changes at the proper intervals, you may be one of the lucky ones to go a million miles before anything major goes wrong.

Stick with the data sheets so that your engine doesn’t fall prey to the wrong advice or information. It is the best protection you can give this motor.

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