i bought my 05' gt 4 months ago with 83k miles on it and its time for an oil change... i usually use castrol gtx on my cars.... but i have no ideawhat oil the previous owner was putting in, my question is is it too late to use royal purple in my car?

 

No it's not.

 

nope change and enjoy your car.

 

I had a problem with Royal purple on a higher mileage v6 that I had. It leaked past the oil pan seal. I had the oil pan seal replaced because the dealership I bought it from has amazing customer service, they fixed it for free (I didnt realize it was the royal purple until later). I continued to use royal purple and it started leaking past the rear mean seal. I would use royal purple, but if the car starts leaking (And by leaking I mean probably a drop every few days), then I would switch back.

 

That's not because of synthetic, that's because seals and gaskets wear out and break down.

 

Exactly

 

Correct you are. Dino oils can prolong bad seals, but that doesn't mean synthetics are destroying them. It means a synthetic will expose what needs to be fixed, not band aid the problem like a dino oil has been known to.