Manual Transmission Fluid (Thread 2.1)

[jayjaya29]

He mentions there's no copper corrosion difference. Synchros in the 420G are brass.

Yellow metal = copper and brass

[Zack]

Royal purple synchromax is really good, butter smooth shifting!

[ac427]

Royal purple synchromax is really good, butter smooth shifting!

How old was the oil before you changed to Royal Purple?

Have you run any other gearbox oils?

[Tbonem3]

Royal purple synchromax is really good, butter smooth shifting!

RP mention in 2026

[ac427]

I think i have tried them all over the years.

The RP didn't was anything great. I found new MTF-LT2 to be as good. The Redline stuff has been really good though. Still any new oil is going to be better than old oil.

[Obioban]

RP mention in 2026

lol, exactly. Thought we were finally over it.

[maw1124]

lol, exactly. Thought we were finally over it

🤣🤣🤣

I had forgotten all about them.

maw

[chris719]

He mentions there's no copper corrosion difference. Synchros in the 420G are brass.

Brass is copper and zinc.

[CrookedCommie]

Correct, my point was that the video linked only mentioned copper corrosion difference, not brass or zinc, which is dependent on the EP additive they have. I haven't messed up a 420G or a ZF320 running GL-5 yet, but I have messed up two running Redline D4 ATF, even though they claim it's GL-4 compatible. So use whatever fluid you want, but be aware of the risks.