is it true once you go to synthetic oil you shouldnt go back to normal oil or youll mess up your engine? it happened to my brother when he tried goin back he blew i think a piston ring or a head gasket on his town car?

 

I don't know of any truth to that.

 

You can switch back and forth, mix them, do whatever you want. The two types of oil are fully compatible with each other. I seriously doubt he "blew... a piston ring or a head gasket" because he swtched from synthetic to conventional motor oil.

 

I have switched back/forth and had no probs..... But now I stick with synthetic, because its been proven that it help the engine run cooler...

 

do you think that royal purple is the best synthetic or what do you think would be the best?

 

To answer your first question, no it will not hurt an engine to swithc back and forth between oils. I was told this directly from one of the major brands by email.

As for what is the best synthetic oil, you will probably get 10 different answers. My choices would be Castrol Syntec, Pennzoil Platinum, or the Havoline synthetic stuff.