Ever hear someone tell you that too little oil in your engine is better than too much? This is my experience with this.... I just fixed my uncles truck because of overfilling the oil. One morning he checked his oil preparing for a long trip. It read 2 quarts or so down. The truck is a 94 Chevy 1500 4.3L by the way. Anyhow... he added 2 quarts. He then took off and drove about 10 or so miles (so he says). The truck started losing power and ended up skipping and misfiring. He pulled over, check the oil again and this time realized that he had overfilled the oil by 2 quarts. For some reason he misread the dipstick. He then limped it home, drained the oil and replaced the spark plugs that were all covered in carbon. After messing with it himself for a couple days he brought it to me with a serious running problem. After some simple diagnostic procedures I found there was no compression in the #4 cylinder. I then removed the passenger valve cover to find a broken pushrod, and a rocker arm off to the side. At that time I check to see if the valve was opening and closing properly and noticed it was jammed. What happened? In the short time he drove the truck with too much oil, the carbon from the oil splashing up and sucking in through the pcv valve, piston skirts etc... it had built up a huge amount of carbon in the cylinders. This built up on the exhaust valve, bound it up which slowed itself from closing and the piston hit it bending it slightly. Long story shorter.... I started at 8am... pulled the head off, replaced the valve, reseated it, and put a new pushrod, head gasket, intake gaskets etc.. and had the truck purring like a kitten by 5pm (pat on the back) this included a sit down lunch, and parts chasing. Is too much oil worse than too little? YES!!