I went to the Jiffy Lube this weekend and thought I'd splurge and put in some Castrol Syntec as they were having a sale on it, (vehicle 2007 Toyota RAV4). When I asked for the Syntec the guy said that once you go to a synthetic oil, you should stay on it and not go back to regular oil. Well since the the regular cost of a Syntec oil change is double, I said forget it and just put in regular oil.
First, is it true what the guy said about it being "bad" to go back to regular oil after using synthetic? If so, why? I had a car in early the 90's that loved Mobile 1, ran great on it, I dont remember dedicating that car to Mobile 1 though for all time, I'm sure I used all different oils.
Thanks Rick