When Mobil 1 was introduced to the public for sale, they had an ad offer to call 1-800-askmobil. I did call, and received in the mail, an enormous manila envelope full of data, most of it due to testing with General Motors. GM was interested in the synthetic oil's ability to withstand high temps and still perform adequately. It turns out that the Corvette was getting so cramped under the hood that GM was having trouble fitting an oil cooler. The Mobil 1 was tested against Mobil's best non-synthetic, using dynos to run the motors, supposedly up to and including failure. The engines run on dino oil did in fact fail. The engines on Mobil 1 were mostly still within factory specs, not needing a rebuild. Since that time, many GM performance engines have come with an oil filler cap stating that for warranty purposes, you must use Mobil 1. There is little doubt that synthetic is superior to dino, the question is, is it worth it to you. If dino is changed regularly, it may well be adequate for your uses. I like the safety margin, and have run some engines an incredible number of miles with no failures, using synthetic. It's good that we have choices.