GL-5 Synthetic

[AlphaAssault]

Will a synthetic GL-5 manual transmission fluid eat the brass syncros in our transmissions? Regular GL-5 fluids will, but i wasnt sure about synthetic.

 

[DeNoZZo]

I have heard that reg gl5 will.

I had the same question when I had to change my tranny fluid and I could never get a clear answer. I ran mobile 1 synthetic that "exceeded the standards of gl5" in my tranny for a month until I put bg synchroshift in and I had no problems... other than somewhat notchy shifting on certain days.

 

[talonturds118]

You dont always want the craziest oils in the trans. Theres alot of friction that needs to be there between the speed gears and the synchros to be able to shift. If its too slippery, then the synchro wont be able to match up with the gears, causing it to grind. I put slick 50 in mine and it grinded every single gear. Changed the oil and it was fine.

 

[the_mork]

Not all GL5 oils will eat yellow metals. I know that the Amsoil GL5 is safe for yellow metals so you could use that or Redline is considered a good tranny oil.

 

[AlphaAssault]

Its the sulfur in the old dyno oil GL-5 stuff. but do these new synthetic oils use sulfur as a modifier or not?