Do not overfill this engine. One of the things you have to be careful about is refilling the oil tank. There are some older C7 engines that may take over 20 quarts of oil, but most only take 19 or 20 including the filter. If you add too much, your engine will do everything it can to get rid of the extra oil
You may find that some oil change service stations will try to put 28 quarts of oil in your C7 engine. However, that is 8 and 6 quarts too much. The C7 with the deeper sump only holds 22 quarts while the smaller sump only holds 20, including the filter.
To learn more about this topic, just continue to read our article. It has the information you want to know about as engines do not work that well when their oil tank is over-filled. Take a few minutes to see how this important information will help you.
There are two types of oil tanks or sumps on a C7 engine. One is deep and the other is shallow. The latter option is on about 80% of self-drive RVs. When you do an oil change you need to keep in mind that the oil filter will hold 1 to 2 quarts by itself.
The shallow sump design only holds 17 quarts plus 1 to 2 for the filter. That means you should only have to fill the oil tank with 19 quarts of oil not including the oil filter. Some owners will say 17 plus the oil filter oil capacity.
No matter what, you should not be putting in 28 or 29 quarts like some owners have been told. If the oil change service says the engine takes more oil than the 20 or 22 limits, do not pay for it as you will be losing that oil as you drive.
This engine does not keep the extra engine oil and it will sound and act worse than if you underfill the oil tank.
You do need to learn how much oil your C7 engine holds. If you put too much oil inside the oil tank, you may be spraying oil all over the different vehicles on the road or the road itself. The excess does not help the engine and may create too much pressure that will damage one of the components or more.
There is talk that the oil tank is the same size, it is just the sump that is larger and holds more oil. The reason this was designed that way was to increase the time between oil changes.
Be careful when reading your manual. Sometimes a mistake will get published as in 2007, the manual stated you needed to fill the oil tank with 21 quarts, not 19. You can’t always go by the book when getting capacity information. Mistakes do take place.
We know that many oil change experts in service stations or oil change companies make mistakes as well. They will say 28 or 29 quarts for whatever reason they may have. But they would be in error and you need to double-check to see that they do not put too much in the oil tank.
The type of oil that you would use will depend on the year your RV was made. If it has a C7 engine made prior to 2007 then it will take regular diesel engine oil (DEO) and you can use a 5 W 40 synthetic option or a 15 W 40 or 10 W30 version.
If your engine was made in 2007 or later, then you have to use an ultra-low sulfur oil made to meet the 2007 EPA standards. That oil version will be the same viscosity at 15 W 40 and 10 W30 regular oil and 5 W 40 for synthetic.
This information comes from the caterpillar owner’s manual of 2010, which has the same information as the 2009 version of the owner’s manual. Some websites may only talk in gallons when it talks about the oil capacity of the C7 engine.
They will write figures like 4.75 for the shallow sump and 6.75 for the deep pump. However, when you multiply by 4 you will see that the 6.75 option is too much oil. It comes out to 27 quarts and that is 5 too much approx.
The 4.75 is correct and it comes out to 19 quarts.
The Caterpillar owner’s manuals state that you should use the CAT brand of oil products inside the C7. But the reality is that any major oil brand of diesel engine oil will work in this motor.
As long as the brand meets the CH-4 15w/40 oil standard, you should be fine. The difference will come in when you go from a pre-2007 C7 to a 2007 and beyond C7. The type of oil switches with the latter and must be compatible with low ultra sulfur motors. That should be labeled CJ-4 and it can be used in pre-2007 C7 engines.
But the CH-4 motor oil cannot be used in the post-2007 C7 motors.
Watching how much and what type of oil you use in your C7 engine is important. Too much of a good thing can cause you a lot of performance problems and possibly damage engine components.
The same goes for the type of motor oil you use. All engine oils are not made the same and you need to get the right type for your 2007+ C7 motors. You may be able to use different brands but you are not allowed to use different types. Be careful and double-check when you have someone else doing the oil change for you.