Ive heard great things about Amsoil in cars i have never ran it in my car but i run it in my sled and love it, its very clean. I to run mobil 1 full-syn. however i am bios against royal purple i changed my clutch on my eclipse and decided to try there expensave synctomesh **** and with in 500 miles i was taring out the trans again because i blew the diff up. so i blam that **** not knowing if it was that at for sure, but you have to blame something.