Even though the factory fluid in these cars have a synthetic mixture, has anyone logged a number of miles on a full synthetic such as Red Line, Royal Purple, etc to see if there is any harm in changing over. Thanks for the info.

 

I'm about to change mine over to Royal Purple Syncromax this weekend, I'll keep everyone updated.

A buddy of mine rebuilt a 1998 Corvette from the ground up, it was a salvage title car that was in collision. He just swtiched his 6 speed to Royal Purple and the increase in shift smoothness was noticable even to me as I have driven the car several times before and after the transmission fluid change.

My buddy swears by the stuff, he had it in his 6 liter GTO and CTS-V.

 

I ran Mobil1 synthetic ATF in my '03 Sunfire (F23 Getrag) for 3 years with no problems. Shifted smoother during cold winter weather than my Cobalt with factory fluid does now (same tranny). I will probably make the switch this spring.