Rear end Gear lube

[rod]

just remember, for U guys who are running posi/trac-loks or whatever [any thing besides a spool], do NOT use synthetic lubes. same goes for brass syncro transmissions.
Rod in AZ

[6130]

I ran ATF in the rear end of my Mazda...

[Greg Jones]

My 12 Bolts have done great running Torco 85-140 with pro gears, backlash clearance makes a difference with the viscosity lubes you use also. Synthetic is more slippery and somewhat thinner than mineral based lubes, tight clearances can benefit from synthetics.

[Isaac Zane]

Mobil 1 Syn Gear Lube 75W-90. Great in manual transmissions as well. Works great in Harley transmissions too. 160k miles going well! Knock wood!

[e vassar]

Originally Posted by Billy Nees

ATF

Billy...how much?.
I guess I have to pull the cover off to make sure I get all the old lube out?

[Mike Rietow]

GL-5 is the key ingredient to look for drag racing.

[Mike Rietow]

GL-5 $4.97

[Dave Gantz]

Originally Posted by Mike Rietow

GL-5 is the key ingredient to look for drag racing.

Hi Mike, just wondering, why?

[Rory McNeil]

Originally Posted by Dave Gantz

Hi Mike, just wondering, why?

I`m curious as well. I had been told that the main difference between GL-4 and GL-5 gear oils, was that the GL-4 was designed for use in manual transmissions with "yellow metal" syncronizers, like brass/bronze, and the GL-5 was for syncros with paper or carbon fiber linings. It seems that finding GL-4 gear oil is not as easy these days, GL-5 seems far more common. For the Toploader 4 speed in my street car, I have been using GL-4 Brad Penn, seems most of the major oil companies have just GL-5.

[Mike Rietow]

Originally Posted by Dave Gantz

Hi Mike, just wondering, why?

I run US Gear, when I asked what they like to see in gear oil, they said GL-5 is the key ingredient drag racing.

Valvoline High Performance gear oil is GL-5

Valvoline regular gear oil is not.

Here's a mention in dragzine confirming they're recommendation. No technical terms though, I couldn't find anything other than this.

I just use $4.97 Valvoline GL-5 80w 90. Ford 9" Strange chunk, I've had several different gear ratios in. 3.90, 4.10, 4.33. 4.56, 5.00, 5.29

3200 lb 23 n/a sbc 1.27 60 ft

https://www.dragzine.com/news/lubric...r-in-gear-oil/