My real world experience. Bought a new 95 Neon, after a few miles, I switched it over to Mobil1 and a Mobil1 V6 filter. That engine up until a piston broke due to something not related to oil, would go 10,000 miles and use about 1 qt. The piston broke at 450,000 miles and the two biggest things that syn did was the inside of the engine looked new, no sludge anywhere, that block could have just been washed out and reused, which I did. The other thing was that the bearings were not in serviceable condition, but within NEW limits.