IMO I used royal purple in my 05 GTP. I had ALOT more done to that car and LOVED the royal purple. When I got the 07 I changed all fluid and added Royal purple. I went to have my oil changed before a road trip and it was about 500miles away from being 3,000 and the Tech guy asked when is the last time I changed my oil!! He said it looked as if I hadn't changed my oil in a good 6K miles! So im not sure if I got some bad oil or what. But I went back to Mobile 1 Syn. I know he was not bs'in me because he is my uncle! LOL.