What do you guys think? I am going to change the gear oil to synthetic one( Mobil 1 ), and engine oil to (German) Castrol 0W-30. I think its safer to use synthetic for gears plus may bea better fueleconomy, expecially in winter, and I know 0W-30 ( which iscloserto 35 actually)is not 5-20, but feels safer. What do you think?

06GT 26k

 

The factory gear oilis synthetic, I changed mine at 10000, used Royal Purple 75w 140w added the ford friction modifier, I run Castrol Syntec 5w 20w in the engine, I have not had any troubles.

 

Amsoil 0W20 in the crankcase here. Some people here have gone to 30 in their crankcase but I think it's prudent to stick with Ford's recommendation.

 

Does GT have synthetic in the gearbox or differential? I though only differential, I am talking about changing oil in the gearbox...

 

Amsoil is the best. I plan on using it when I change out my differential next year.

 

RP already has friction modifier in it you shouldnt need to add more.

 

You will still need the modifier. I don't care what they say. Been there, done that.

 

Another Amsoil user here. I believe it is the best.

 

No problems at all here, to many have said not to add more for me to change my mind.