I just wanted to point out that it's not the oil that makes the engine run hotter. It's the fact that in order to get a good tune with high oil content, one must lean the engine more then they would with less oil content to get the same performance. Often with high oil content fuels 12%+ you can actually start to run lean trying to get a good tune and that's where the higher temps come from. I have heard that engines have been tested to as low as 4% oil content and there was no signs of extra wear, this was conducted on on-road high rpm race engines but the oils were of the highest quality. Personally I like to run 8% oil content so I have just a little extra protection, but not too much. Like the saying goes, too much can be just as bad as too little.