Rear Gear Lube - Synthetic Or Conventional?

[Myron Piatek]

I'm an Amsoil user as well. When I can, I break in the gears and bearings with conventional fluid, just like an engine. I was also told that the OEM gear coatings are not good for the gears and bearings afterwards. So a flush to eliminate that as well as any initial metal wear seems like a good idea. Then I go to the Amsoil Severe Gear 75w-90 synthetic. I just checked my 8 3/4" gears after several years of running. They were much better than expected so I put them back in. Unfortunately, I have yet to count the # of runs I get on some of my parts.


If you have the gears REM surface finished, you won't have the coating to worry about. But it's best to set the gears up before REM because it can be difficult to get a pattern reading, according to my differential guy.

[Shake & Bake]

I use Amsoil Severe Gear Sae 75W-110 Synthetic Extreme Pressure Lubricant. It's a premium grade extreme pressure (EP) lubricant engineered specifically with "High Film Strength" for high load demands.


It's also compatible with conventional and synthetic gear lubes and most limited slip differentials.


Plus it's recommended for applications requiring 75W-110, 75W-90, or 80W-90 gear lube with any of the following specifications: API GL-5, MT-1, MIL PRF-2105E, Dana SHAES 234 (Eaton PS-037), Mack GO-J, or the differential gear lube specifications from GM, DaimlerChrysler or Ford.

[Ed Carpenter]

Redline heavy duty shockproof in my Dana no problems.

[Rory McNeil]

Originally Posted by deuces wild

Redline heavy duty shockproof in my Dana no problems.

Same here, (and light shockproof in the Jerico)

[Brett C]

We run all Strange products with Royal Purple. Never had an issue. (Knock on wood)

[ATI Performance Products]

Originally Posted by Brett C

We run all Strange products with Royal Purple. Never had an issue. (Knock on wood)

We have run Qualifying Driven oil in the Challenger Rear with no issues and a 4.88 until I went to 3470+ lbs. At 3250 no issues for 2 season. At 3470 we hurt gears. They are not Pro Gears and its only an 8 3/4.....so keep that in mind.

Switch to the Driven's Speedway Synthetic oil in Challenger and have always ran in COPO with no issues. Its VERY light.....

I do break in for 3-4 passes with No Synthetic Driven Break in or Torco oil from Mark Williams.

As far as an A to B to A test - never done - doesn't matter since I won't run a light weight non synthetic in the rear or trans anyway - we have enough other **** to test when we go out!

[THE LEGEND]

Amsoil Severe Duty for me

[Shawn Blair]

Originally Posted by ATI Performance Products

We have run Qualifying Driven oil in the Challenger Rear with no issues and a 4.88 until I went to 3470+ lbs. At 3250 no issues for 2 season. At 3470 we hurt gears. They are not Pro Gears and its only an 8 3/4.....so keep that in mind.

Switch to the Driven's Speedway Synthetic oil in Challenger and have always ran in COPO with no issues. Its VERY light.....

I do break in for 3-4 passes with No Synthetic Driven Break in or Torco oil from Mark Williams.

As far as an A to B to A test - never done - doesn't matter since I won't run a light weight non synthetic in the rear or trans anyway - we have enough other **** to test when we go out!

I don't know that it's an oil issue. I bracket raced my Dart with the 8 3/4 for ten years at around 3250 lbs. When I started running it in SS/JA a 3470+ lbs. I took teeth off the gears three times. I switched to a Dana, haven't touched it since and I'm running the qualifying oil. IMO it's more of a gear strength issue and I don't think it would be an issue if pro gears were available for the 8 3/4 in the ratios we need them. Just my 2 cents

6383 SS

[Dave Noll]

This is my first go around with Redline in the diff.. Using super light shock proof, I'm @ 3650 w/me but I'm slow. 5.14's in a 9".

[Jeff Niceswanger]

Originally Posted by deuces wild

Redline heavy duty shockproof in my Dana no problems.

Ed , You have a PM ... Jeff