transmission oil- GL-5 vs.GL4

Most GL-5 gear oils have an additive that is corrosive to the syncros/rings in the SR tranny, that is why the book recommends GL-4. I wanted to use Royal Purple gear oil in mine when I installed my ACT...so I called Royal Purple and asked them about it because theirs claims to be safe for all applications calling for GL-4 and GL-5...the tech said that they do not use the same type of corrosive additive, that is is safe to use. I have been using it for about 3-4 months now, and I know there are a few others that use it as well...I would make sure it is GL-4 from any other manufacturer though...

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Brad B. 96 SE-R
PR CAI,HS Gen 4,ACT,ES motor mnts,1.8 dropw/AGX's,F&R STB's,17deg timing,91 intake cam,NGK wires,205/40/17 Kumho 712's,SMC short shifter,Royal Purple synthetics..AND A VANILLA AIR FRESHENER!

It won't go KABOOM...it will slowly eat away at your syncros...but hey, if Nissan Monkeys told you go ahead...well?

I wouldn't unless Mobil One stated that it is safe for GL-4 applications. Just my .02

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Brad B. 96 SE-R
PR CAI,HS Gen 4,ACT,ES motor mnts,1.8 dropw/AGX's,F&R STB's,17deg timing,91 intake cam,NGK wires,205/40/17 Kumho 712's,SMC short shifter,Royal Purple synthetics..AND A VANILLA AIR FRESHENER!