Rear Gear Lube - Synthetic Or Conventional?

[69camz28]

I have a Strange S60 (Dana 60) in a 69 Camaro. I had it re-geared recently to a 4.30 gear and it has a Tru-Trac carrier. I was told that the gear company (Motive) recommends conventional gear oil - 75/140, and not to use synthetic gear oil. Thoughts on this?

[tim worner]

have used 75/90 syn lube for years no problems

[Mike Pearson]

Originally Posted by 69camz28

I have a Strange S60 (Dana 60) in a 69 Camaro. I had it re-geared recently to a 4.30 gear and it has a Tru-Trac carrier. I was told that the gear company (Motive) recommends conventional gear oil - 75/140, and not to use synthetic gear oil. Thoughts on this?

Is the tru track a posi unit? if so use what Strange tells you to use. if it has a spool and is race only the synthetic works fine. I use it in my Dana race only with spool.

[Dragsinger]

just in the last season or two I have been pushed with some resistance to trying synthetic oils. I am pleased with the results to the extent that I bought into an Amsoil racers program.

Amsoil was in the very pioneering phase of synthetic engineering. They have good proven products and support a wide range of sportsman racing.

I think Amsoil products are a good choice and will be running them in the Super 10.

[69camz28]

A True Trac is: The Detroit Truetrac is a helical-gear style performance differential that maximizes wheel traction and enhances driving and handling characteristics.Operation The Truetrac operates as a standard or open differential under normal driving conditions, allowing one wheel to spin faster or slower as necessary. When a wheel encounters a loss of traction or the terrain changes, the gear separation forces take effect and transfer torque to the high-traction wheel. The helical-shaped gears mesh with increasing force until wheel spin is slowed or completely stopped. When the vehicle exits the low traction situation, the differential resumes normal operation.
Performance Operation of the Truetrac is smooth, quiet and automatic. The unit will engage without any driver knowledge or action required. It also has no wearable parts and requires no maintenance, meaning less time in the garage and more on the road.

[Geerhead55]

I'm using synthetic lube in my 4:30 geared Dana 60 as well,, it has a spool.
Danny Durham

[Lou Jeffery]

Whenever the subject is Synthetic or Conventional the responses always say "We run it and have no problems". So we understand that there are no negative effects but what are positives? ET, durability, consistency?

[Dragsinger]

Lou, good question. I have some feedback and will work it up and post later.

[Jon Sarrett]

I think this is one of those ask 10 people and get 10 different answers kind of thing. I run Royal Purple synthetic in my Plymouth but run what Strange recommended (and sent) in my Camaro. The brand name escapes me but it was a non synthetic oil.

[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.