Muncie gear oil recommendations

[Motorhead848]

Looking to see what everyone is running for gear oil in their muncies.... autogear says royal purple max gear, but it’s a synthetic and have heard about leaks with the synthetics. Also they recommend joe Gibbs driven 80/90... everyone seems to be changing formulations these days so I’m not sure what to run!

Thanks

[NorCam]

I've been running Brad Penn GL4 80W90 petroleum based gear oil the past few years. No leaks, no worries and just about everyone including Auto Gear and Midwest Muncie says yeah...good stuff. Nothing wrong with Joe Gibbs either as far as I'm concerned.

[Motorhead848]

That’s where it gets confusing! That’s what I was planning on running but I’ve heard they have reformulated it and it’s no good for the synchros so they (autogear) are no longer recommending it....they are saying RP or the joe Gibbs.

[69L78]

Sta-Lube API/GL-4, I get mine from NAPA

[GrumpyJeff]

Originally Posted by 69L78

Sta-Lube API/GL-4, I get mine from NAPA

Yep, this stuff !!!

[big gear head]

https://www.youtube.com/watch?v=Z7NpsMZ9pBQ&t=1062s

[x33rs]

Originally Posted by 69L78

Sta-Lube API/GL-4, I get mine from NAPA

That's what I've used for years. No issues.

[seventieshow]

Originally Posted by 69L78

Sta-Lube API/GL-4, I get mine from NAPA

Me too. The GL-4 is the thing to look for for older transmissions with brass synchronizers, not GL-4/GL-5 or GL-5. I think Amazon sells it as well.

[novadude]

Originally Posted by NorCam

I've been running Brad Penn GL4 80W90 petroleum based gear oil the past few years. No leaks, no worries and just about everyone including Auto Gear and Midwest Muncie says yeah...good stuff. Nothing wrong with Joe Gibbs either as far as I'm concerned.

Me too. I was using the sta-lube, but I think it shifts just a little bit smoother with the Brad-penn, especially when cold. Not a huge difference though.