Can someone explain to me the technical reason why it is damaging to have too much oil in an engine? My driveway is a mudpit so I took my car to prompto and they put in like half a quart too much. I am thinking of writing them a nice little letter...

Half a quart won't do anything. Too much oil though can cause extra friction actually, although it seems odd. I put in half a quart extra as a personal preference.

I have heard that the engine can actually over pressurize with to much oil. Causing you the motor to blow alot of gaskets! :(

I think too much oil, like a quart too much, will cause what you call windage losses associated with the crank churning up your oil. This causes pressure build-up, and blown gaskets, and stuff.

I went over almost a quart a few months back, cause I drained the oil with the car still on the jack! I definitely noticed a difference right away, and drained some.

Having too much oil will make it seep out into the air intake line that goes into your valve cover. If that happens, you will see a lot of smoke coming out of the tailpipe & your car will drive very funny. Then you'll ruin the oxygen sensor & other sensitive things. Always check your oil level on a FLAT, no angle, surface because the SR20DE engines seem to be sensitive about that. Don't go any higher than the MAX line. You can still slide by if the oil touches the bottom of the "H" (HIGH) or "I" mark on the dipstick, depending on how you're looking at it, but I wouldn't recommend it. The comments above are also pretty acurate. :D

Well I still believe more oil is better than less oil.