AHHHH! Bail out and head for the hills!
Okay, ... Seriously, of all the things people have done to their cars, this is not something to lose sleep over. First of all, you'll notice that if your dipstick is like almost all others, it doesn't say "full" and "add". All engines today use a little oil between oil changes, and to address the numerous complaints of oil usage, most manufacturers have changed to "Min" and "Max". As long as the level stays between the two limits, there is nothing to worry about and nothing to complain about.
As for being a little over-full, the worst thing that can happen is the spinning crankshaft can whip up the oil and whip air into it. Unlike oil, air can be compressed, and that reduces the oil's ability to isolate moving parts. In other words, where there is supposed to be a gap of a few thousandths of an inch between the bearings for the crankshaft and connecting rod journals, lack of oil could allow them to bang against each other and cause excessive wear. That aerating of the oil is more likely to occur at higher engine speeds, but I'd pretty confident even a quart over-full won't be enough to cause this to happen.
The worst I ever saw was a fellow mistakenly checked his oil while the engine was running, so of course it would appear to be low. He kept filling and filling until it read "Full", but he had to add five quarts to do that. It was a Volkswagen diesel, and it only held about five quarts.
Being seriously over-filled, by the time he got across town, the foamy oil was sneaking past the piston rings and the engine was running wide open on it. Oil is fuel to a diesel engine. I grabbed a handful of cloth towels, dunked them in a water tank, and ran over to try to snub the engine off, but by the time I got there, air bubbles were steaming out of every gasket on the engine. It slowly died right there on the side of the road. Now THAT was over-filled!
If you still are worried, just remove the oil filter, empty it, and put it back on. If you try to remove a little oil by removing the drain plug, you'll just make a mess, and you'll remove too much by the time you get the plug back in.
Monday, February 16th, 2015 AT 11:55 AM