I never knew this but...if you check the engine oil while you're car is running, is it supposed to give a lower reading? Mine does. When I check it while the engine is off, it is normal. I guess the oil flows throughout the engine. I could have sworn I've checked my oil before while it was running (maybe in another car) and I don't remember ever knowing that. I thought I had an oil leak-the "LOW OIL" light stayed on after I cranked it yesterday, but I guess it got hung up. There was a little fresh oil on the passenger side valve cover, but I checked everywhere else and no leaks. It may be leaking very little at the hose on that valve cover (some sort of breather). What can I do to stop it?

 

you will definatly read less oil when the engine is running... i always wait at least 5 minutes after turning the car off if i want to check the oil... you gotta wait for it to all drain back down outa everything... but that shouldn't turn on your light...

 

No car out there will specify checking engine oil while the engine is running, since there is no way to get a reading properly when not all of the oil is in the pan.

You're thinking of an auto trans, which often needs to be checked with the engine running.

I found last weekend when I checked my oil level cold overnight, on an extremely cold night I might add, that it showed to be down a bit, which I knew wasn't true since I just added oil the week before. So I drove it 20 miles and then checked it about 15min after shutdown and the level was full. I think that in the winter this method is the best way to check oil.