My friend had a Porshe 911 Turbo, he had heard amazing stories from Amsoil after visiting the States middle last year, confident that it would give him the most protection that he needed and the ultimate amount of horses he required, he switched to Amsoil after the 1st service interval,(6250miles).
Hadn't had the oil in for 1000miles, had done nothing out out of the ordinary, pushed it but not over board, and his engine blew! Porshe say now they won't carry the cost because he used Amsoil and not the prescribed lubricant they suggested for the car, and that if he wanted to keep the warrenty on his car, he should have used Mobil 1.