I would assume most vehicle dip sticks are set up to check the oil with the engine hot and after having just been shut off perhaps when stopping for fuel.
In fact my manual specified a range of temperatures at which they want me to check the oil. Basically normal operating temperatures - not after just having pulled a steep mountain grade with the oil really hot and expanded to the max.
I seem to remember that one of the big problems with over filling a crankcase is that the crankshaft can possibly start "slapping" down into it to cause foaming. And then maybe the oil pump pickup screen will start sucking foam instead of good solid oil.
But I'm not a gear head, so maybe that' an "old wives tale" or something.
Maybe we should all check the oil hot one day and then the next morning when cold and notice what the difference in level is. Just how much oil drains down into the pan overnight? And how much does it "shrink" when cold?
