Originally Posted By: turtlevette
An extra quart provides extra heat sink. I don't think oil froths anymore. They put in additives to prevent that.
hmmmmm...as a heat sink, as you'd be aware, you only get to heat it up once, then it's job is done...how much extra heat does a single quart of oil store on warm-up, and how is it relevant 10 minutes after ?
Cooling surfaces like sumps and blocks and rocker covers haven't grown in surface area, so there's little means to move any more heat out of the engine by that extra quart.
A (20%??) improved sump residence time isn't going to mean much if the sump isn't moving more heat.