RTV seals?

Status
Not open for further replies.
Joined
Oct 28, 2002
Messages
49,065
Location
Everson WA - Pacific NW USA
I saw this on the Amsoil application guide:
quote:
3. Do not use Synthetic Lub in axles using RTV. Synthetic Lube will chemically atack RTV Sealant.
It was under "capacities" for a 2003 S-10 Blazer front differential. Amsoil doesn't write these capacities, they simply buy compiled application books. You automotive folks know what I'm talking about. First of all - how common are RTV seals? I know there are RTV gaskets and such, but seals? And most importantly, where did they get that scoop? Plenty of cars use RTV GASKETS - including mine. No leaks with synthetic in over 10+ years.
 
Joined
Dec 1, 2002
Messages
231
Location
Ontario
I have used RTV gasket maker on numerous differentials with Amsoil and never had a leak. I do seem to remember someone on here saying that GM did not recomend using their own OEM syn gear oil with RTV because of possible leaks.
 
Joined
May 25, 2005
Messages
4,009
Location
Calgary Canada
I have been using synthetic differential lube with RTV gasket maker sealing the diff cover for quite some time now. I haven't seen a problem yet.. I'm interested in hearing more about this.
 

01rangerxl

Site Donor 2021
Joined
Apr 8, 2006
Messages
10,667
Location
Birmingham, AL
My truck has had fully synthetic Motorcraft 74W140 in the rear axle and RTV gasket maker sealing the cover for about 1.5 years now and it is not leaking any oil. It's the black RTV if that matters.
 
Joined
Jan 20, 2003
Messages
18,448
Location
East of IGO
quote:
3. Do not use Synthetic Lub in axles using RTV. Synthetic Lube will chemically atack RTV Sealant.
SEALANT
 
Joined
Aug 11, 2004
Messages
2,386
Location
Chicago area
There are many gaskets, head, intake, and valve covers, that use RTV integrated in their design. But, Amsoil is referring to tube type RTV sealant.
 
Joined
May 25, 2005
Messages
4,009
Location
Calgary Canada
Just to be clear, my diff cover is sealed with RTV, squeezed out of a tube like toothpaste. There is no gasket whatsoever. This is the Permatex blue RTV. Are we talking about the same SEALANT here?
 
Joined
Dec 22, 2002
Messages
4,714
Location
The Garden State
quote:
Originally posted by Jim 5: Just to be clear, my diff cover is sealed with RTV, squeezed out of a tube like toothpaste. There is no gasket whatsoever. This is the Permatex blue RTV. Are we talking about the same SEALANT here?
I used this same product when I had my rear diff fluid changed to MolaKules 75W-90 synthetic gear fluid. It developed a severe leak after 6 months. It didn't leak at all before that, which was strange. I was forced to have Ford put in their 75W-140 synthetic gear fluid using their expensive rtv sealer. But so far after 8 months I've had no leaks. Maybe there is some truth that synthetic gear oil can "eat" away at some rtv silicone gasket makers [I dont know] . Whimsey
 
Joined
Jun 21, 2003
Messages
209
Location
Spring TX
I have a 2000 Ranger that has no gasket on the differential cover either, only RTV. I used Permatex Black to reseal the cover when I refilled with Molakule's HDS-5 synthetic product. Not a seep or drip after 2 years [Big Grin] [Cheers!]
 
Joined
Aug 11, 2004
Messages
2,386
Location
Chicago area
For automotive use, use black or red RTV, NOT clear or blue. Trust me on this. Of course, there are better specialty RTVs in gray and copper.
 
Joined
Mar 21, 2006
Messages
10,610
Location
Las Vegas NV
I just put AMSOIL dif. lube in both my Ranger and Jeep a couple of weeks ago. I bought the Chrysler dif. RTV from the stealership. It was a gray color which I was surprised by. No leaks so far.
 

Pablo

Thread starter
Joined
Oct 28, 2002
Messages
49,065
Location
Everson WA - Pacific NW USA
I must have been really tired when I posted that. It clearly says "sealant", my brain read "seals". Weird. I have been in the meat grinder for over a week...anyhow I got an answer from HQ:
quote:
In response to your inquiry, we are in the process of removing that statement as it does not apply to Amsoil's formulations.
 
Joined
Jun 2, 2003
Messages
1,172
Location
Long Beach, CA
My situation is like others above...rear diff (Ford 9.75") requiires RTV only for the gasket...and Ford wants you to us synthetic gear lube. Never had a leak...
 
Joined
Apr 17, 2012
Messages
3,431
Location
West Michigan
On a Ford 9.75 with 75w140 MC synthetic oil and friction modifier... would you choose permatex Black Silicone Adhesive Sealant, Gear Oil RTV or Ultra Black RTV?
 
Joined
Feb 25, 2015
Messages
1,661
Location
Sask, Canada
I recently used some permatex blue on both the rear diff and trans pan on my Ram. Seems to be holding just fine on the diff after several months and a few thousand KM.
 
Joined
Apr 17, 2012
Messages
3,431
Location
West Michigan
Originally Posted By: Colt45ws
Necropost alert! Forum post Dead 10 years rises again! Ive always used the Ultra Black on everything and never had any leaks.
Hehe, yeah. I was running a search and figured just to keep it all into one thread! I've used Ultra Black a few times before with zero problems as well. Just never with additional friction modifier. I'll probably go with black again, it seems that despite the marketing there just aren't any issues.
 
Status
Not open for further replies.
Top