Originally Posted By: Kira
"Sigh. This AGAIN? That's what, the 10th guy that's overfilled oil in the last week or so."
Correcting any mistake will get you sharper faster than anything else.
While an overfill of 8 oz. will likely cause no problems, there's no guarantee.
Yep, we just don't know when the crankshaft starts hitting the top of the oil, frothing it up.
That said, it should be reliable enough to simply look at the oil dipstick after a run on the highway for a while, and see if there are any bubbles on it. If none, I'd wager its OK at that level.
Overfilling is a problem. I usually purposely put in about a half to a full quart under "spec", then top it off gradually over the next few weeks.
I thought I was safe putting in 5.0 quarts recently in a 5.3 quart spec (Chevy 1.5L turbo) engine, and I somehow managed to overfill it! I guess 0.3 quarts under spec wasn't enough. I think it was overfilled about 1 cup too, like the OP's engine. I did crawl back under, halfway unscrewed the drain plug, let out about 1 cup, and tightened it back down. A little OCD perhaps. Perfectionist.