2000 Malibu oil overfilled, any damage?

[55Test]

My dad has a 2000 Malibu LS with the 3100 engine, and it's developed a bad rattle or knock or piston slap, some kind of bad engine noise. This knock started a little while before he took it in for an oil change. He took in it to some corner gas station, that was about 2 weeks ago. Just today, he checked the dipstick. It was overfilled! He said he drained out a bit over a quart, and it still read a small bit over the full mark. What are the chances that damage was caused by the engine being overfilled?

 

[Al]

Unlikely. The knock is epidemic and also the chances of the intake gaskets leaking in the first 50K miles is well over 59%. The engine is the biggest piece of junk that GM ever produced.

 

[55Test]

I know GM's 60 degrees V6's make noise, I owned a 2.8 FI, my brother had a 3.1 FI, and they make noise, but this Malibu is just in a league of it's own. It sounds like a loud diesel, and that's when the engine is up to operating temperature. It's worse, if you can imagine, when it's started up in the mornings.

 

[TC]

"This knock started a little while BEFORE he took it in for an oil change." Therefore not oil change-related.

Although possible, short term overfilling is not likely to cause a problem per these two reputable sources. I wouldn't worry much about it, especially if was only a quart over.
"If the oil level is too high (overfilled) the engine will exhibit excessive friction loss (churning), resulting in high fuel consumption, loss of power and possibly also engine damage. Furthermore, the engine will burn too much oil, and so pollute the environment."
http://www.volkswagen-environment.de/buster/buster.asp?i=_content/praxis_1650.asp

"An overfull oil pan may lead to oil leakage through the pan gaskets and seals. Excess oil also can contribute to higher pressures and excessive vapors in the engine crankcase. If the oil level is extremely high, the rotating crankshaft may strike the oil and cause the engine to labor harder. This can reduce gas mileage and actually lead to premature engine wear." http://www.csaa.com/global/articledetail/0,1398,1004010302%7C2024,00.html