Why do you have to check the oil on Cat with the engine running?

[quote="gauntjoh"]I guess the obvious answer is that Cat says that is how you should do it, but what is the reason?
I believe most other tractor manufacturers recommend checking the oil with the engine stopped.[/quote]



I believe because they want all the journals and top of the head filled and all surrounding areas lubricated... In addition to allow for the the warm oil to expand as to not overfill the oil... It is engineered for low idle and a warm engine.....

So on engines for generators or engines in the arctic that should not be stopped you can check the oil level with engine running.

Some have both engine running and engine stopped marks on the dipstick. The major determinant is that there is a shield to prevent oil splash on the dipstick with the engine running.

[quote="gauntjoh"]I guess the obvious answer is that Cat says that is how you should do it, but what is the reason?
I believe most other tractor manufacturers recommend checking the oil with the engine stopped.
Wouldn’t it just be a different mark on the dipstick.[/quote]

So you don't have to shut the motor off and restart it as with a starting motor.
Bob

John,

Pretty much as others have said, when operating a pony started engine, shutting down mid-shift is a pain. If a motor is using oil, it is much simpler to check while running to see if more should be added. We would never shut them down over lunch but the oil "users" would be checked before going back to work. I think Cat was thinking ahead for the long shifts the machines would see in their life. As Marco says, sometimes they are never shut down at all for extended periods.

Just my opinion.

JanM

I can understand the need to check oil level with the engine running but why not have two levels on the dipstick as cc says some engines have? Otherwise how do you know how much oil to put in eg after an oil change?

Toby has a discussion on this topic in one of his latest Squatch253 videos comparing early J series engines with later. Has to do with the oil cooler and other areas being filled with oil.