Stovebolt.com
Posted By: Elmo Gear lube in 53 3600 3/4 ton truck - Mon Jun 22 2020 09:35 PM
How many bottles of 80/90 gear lube goes inside of my transmission?
How many bottles do I need to buy??
Thanks guys and gals...
Elmo
Posted By: Mike B Re: Gear lube in 53 3600 3/4 ton truck - Mon Jun 22 2020 10:10 PM
The SM-420 holds about 6.25 pints of SAE 90 Mineral Oil.

Here's what I use...

https://www.tractorsupply.com/tsc/p...-all-mineral-90-transmission-fluid-2-gal

Mike B smile
Posted By: Spotbiltxo Re: Gear lube in 53 3600 3/4 ton truck - Sat Jun 27 2020 03:29 PM
Would I use this same SAE 90 mineral transmission oil in the rear differential?
Posted By: Wrenchbender Ret. Re: Gear lube in 53 3600 3/4 ton truck - Sat Jun 27 2020 04:51 PM
Originally Posted by Spotbiltxo
Would I use this same SAE 90 mineral transmission oil in the rear differential?

NO! You must use gear lube rated GL5 in the rear end. I like 85/140 viscosity. It also holds about 6 pts.

George
Posted By: Spotbiltxo Re: Gear lube in 53 3600 3/4 ton truck - Sun Jun 28 2020 01:27 AM
Thanks George. I think I’ll make a trip to Tractor Supply tomorrow to pick up some of your recommend gear lube, then change mine. Haven’t peaked inside the pumpkin in the 12 years I’ve owned the truck.
Posted By: Mike B Re: Gear lube in 53 3600 3/4 ton truck - Mon Jun 29 2020 01:25 AM
This is what you use in your rear...GL-5 Hypoid Gear lube rated for extreme pressure.

https://www.tractorsupply.com/tsc/product/traveller-80w-90-gl-5-gear-oil-6-1-quart

Sold everywhere, not pushing Tractor Supply, their links are easy for me to find to give you the specs.

Mike B smile
Posted By: Elmo Re: Gear lube in 53 3600 3/4 ton truck - Wed Jul 01 2020 01:22 PM
Ok now I’m really confused, I’ve heard people say to use a GL5 in the transmission and I’ve heard people use GL4 in the transmission.
Which one is it?
Elmo
Posted By: drdoug Re: Gear lube in 53 3600 3/4 ton truck - Wed Jul 01 2020 02:31 PM
Elmo, GL4-rated fluids are recommended for transmissions. They promote smooth shifting and are synchronizer-friendly, especially important for gearboxes that may have "yellow metal," brass/bronze components. The mineral oil recommended by Mike B. is rated GL1, and OK for older transmissions that don't require a higher level of protection. GL4-rated fluids are better products in that regard, but generally cost a bit more. My go-to is Red Line Oil MT-90 which is GL-4 rated, FWIW, since it's what I keep in my shop to service several newer vehicles.

GL5-rated fluids are recommended for wear protection of the hypoid gears used in rear differentials. Once again, FWIW, I use Red Line Oil 75W90 or 75W140, depending on what's called for, and because it's what I have in my shop for the same newer vehicles (BMW, Nissan).

There seems to be a bit of debate in the forum, but the sulfur content in GL5 fluids may promote corrosion of brass/bronze components, and they are generally not recommended for transmissions (which do not use hypoid gears) and so the increased level of protection isn't needed.

Hope that helps.

Doug
Posted By: Mike B Re: Gear lube in 53 3600 3/4 ton truck - Wed Jul 01 2020 11:08 PM
Some of the newer transmission lubes are to slippery for our old transmissions, it doesn't give enough resistance to slow the gears down when shifting which can causes grinding between gears...

Mike B smile
Posted By: Spotbiltxo Re: Gear lube in 53 3600 3/4 ton truck - Thu Jul 02 2020 02:16 AM
Thanks for the info on diff fluids and the link to what Tractor Supply sells.
Posted By: whateverpratt Re: Gear lube in 53 3600 3/4 ton truck - Sat Jul 04 2020 12:24 PM
The shop in my hometown in Southeast Texas that only rebuilt rear axles swore by using non-synthetic 85-140 in rear axles
© The Stovebolt Forums