I've seen this discussed before..
The theory is, more oil means it has more to stick to parts and help cold starts, and that it stays cooler. Sounds good initially, but.....
I'm not engineer, physicist, or any other type of scientist, but intial thought was comparing it to a pot of boiling water. In very little time, it all gets to the same temperature. Starting with more water just caused it to boil over quicker due to lack of room. This thought, when applied to a sealed system in my mind, led to bad results.
I never bought into it myself. Like other have said, GM has scientists who know this stuff, so the marks must be there for a reason.
1998 SE Midnight Blue Pearl
Gutted airbox, FRAM AirHog, removed MAF Screen, eBay clear corners, extended brake lights
I'm so much cooler online