There's normally a warning not to overfill the crankcase. Remove/suck out the extra quart immediately. It's best to keep the oil level between the max. and min. lines on the dipstick. I'd question the independent mechanic how/why he returned your car to you with the crankcase overfilled. It's certainly not rocket science and his helper should learn how to perform an oil change properly. Most shops use bulk oil and add oil with a nozzle which makes it easy to overfill if one isn't careful. It's best to underfill by a quart or so then run the engine for a few minutes and check the level on the dipstick. Add as required to bring the oil level midway between the max. and min. marks.

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Fred Hoelzle