RTV sealant compatible with synthetic gear oil?

[KilgoreBass]

I just read this on the Amsoil site. I recently changed my rear diff oil to Severe Gear 75W-90, and used Permatex red RTV (high temp) to seal it, will this be a problem?

[6] 1988-99 models
Do not use synthetic lubricant in axles using RTV sealant.
Synthetic lubricant will chemically attack RTV sealant.
American Axle has only approved the use of Synthetic
Lubricant 75W-90 GM part no. 12378261, as follows:
a. All 8.6 inch rear axles are compatible.
b. All 9.5 inch rear axles built before mid-February 1998
(RTV sealant used to seal cover pan) are not compatible
c. All 9.5 inch rear axles built after mid-February 1998
(equipped with cover pan & gasket) are compatible.
d. All 10.5 inch rear axles built prior to March 3, 1999 are
compatible if axle shafthub RTV sealer is replaced with GM
gasket part no. 327739.

Amsoil 92 S10

 

[casper]

odd...the ford 8.8 specifically calls for syn 80W140 and states to use RTV.

 

[tig1]

With M1 75-90 I used Ultra Black and never had a leak.

 

[gamefoo21]

Apparently you need a special type of RTV...

http://www.permatex.com/products/Automot...rtv_sealant.htm

Although Ultra Black and the Right Stuff Grey will also work.

In high temp usage, I tend to prefer Ultra Copper, higher temp, better resistances than the Red.

 

[Chris142]

The regular Blue sealant never worked with any gear oils. Atleast not for me. No issues with the black.

 

[oilboy123]

Funny I have never had a problem. I normally use the permatex copper. Been doing this for at least 15 years

 

[Colt45ws]

Ive been using black since Ive been doing diffys and have not had a leak yet. Though I learned from the other thread it isnt the correct application if you are going to go straight to torquing it down. Grey is for that.
Oh yeah, I have Amsoil SVT in my 8.8 with black. Leak free.

 

[Pablo]

KB - this has been discussed a few times over the years hear at BITOG. Maybe a good test for the "new" BITOG googlelator.

It's actually from a GM TSB, Amsoil is just passing it on. I believe it originally came from or GM working with American Axle. It stems from the type of RTV American Axle used. I don't think it applies at all to Amsoil and any other RTV.

 

[mechtech2]

I have used bunches of RTVs and sealants.
Avoid the clear or translucent blue stuff for car use [maybe windows].

This does not mean the Permatex Ultra blue, which is great!

Get a premium product , thoroughly clean the substrate, and give it plenty of cure time before contact with any oil.

It won't leak.

 

[01rangerxl]

I have had no problems with using Ultra Black RTV on a diff filled with Royal Purple...which is good because that [censored] is too expensive to leak out.

 

[pavelow]

I'm using Valvoline synthetic gear lube in the front and rear axles on the Jeep with Permatex Ultra Copper RTV sealing the diff covers and they have never leaked.

If you are worried about leaks, just get yourself a diff cover gasket and avoid RTV altogether. I'm sure Felpro, ROL, Cometic, Mr Gasket, etc make one for your application. If nobody makes one, just get yourself gasket material and make your own-easy to do using the diff cover as a template.