Out of curiosity, why can't you go back to conventional after using synthetic? People are always telling me this, but no one gives a reason. I recently sold my toyota camry, which had been running on full synthetic for quite some time. When i sold it, the new owner immediately took it and changed the oil, went back to conventional. It had been on synthetic for at least four oil changes....but it is fine now, no problems from going back to the conventional.

No oil change guy has ever looked at me and said "is your car running synthetic or conventional?" and you'd think if it could hurt the car they would not just assume and put conventional in my car.