Dealership filled engine with too much oil...

[Yaris Hilton]

Originally Posted by Sir A.Y. Atoyot

The way I heard it, what happens when you put 'way too much oil in an engine is that the crankshaft counterweights and the big ends of the connecting rods hit the oil and beat it into a froth. Enough of that and the oil pump starts sucking air. Since air is compressible, unlike oil, this can cause an air lock, and goodbye bearings!

Exactly right. My point is that 4 quarts isn't "way too much oil." Toyota's engineers are competent enough not to put their recommended fill level right on the brink of disaster. There's a considerable margin for error.