Synthetic Lubricant & RTV Sealant - Important

[sparg93]

I personally was not aware that you can NOT use synthetic lubricants with standard RTV sealants. As most of us use Permatex Black RTV , this is pretty important stuff.

Technical disclaimer from Amsoil: Check out bulletin #4
http://ww2.amsoil.com/mygarage/VehicleLookupPage.aspx?FromIndex=1&url2=1999+CHEVROLET TRUCKS+TAHOE+R

Forum:
http://forums.highperformancepontia...ain-restoration/permatex-warning-on-sealants/

From what I've read about Permatex "Gear" RTV (this is not traditional "Black"), you can use this with synthetics.

PR release on the Permatex "Gear" RTV: it remarked that it was safe for use w/synthetic lubricants.
http://www.permatex.com/resource_auto_press/pr_auto_7910.htm

Data Sheet on Permatex Gear RTV:
http://permatex.com/documents/tds/Automotive/81184.pdf

 

[SunlitComet]

we have the 8.6" axles and ares are compatible with synthetic gear oil. don't worry.

 

[sparg93]

we have the 8.6" axles and ares are compatible with synthetic gear oil. don't worry.

What about the front diff? Is it standard RTV from the factory or paper?

As an aside, I rebuilt a 14bsf and slapped it in the rear...I used standard black RTV then poured Royal Purple in it I guess this will force me to change the oil out in a few years when the RTV is eaten through (always a good thing I guess)

 

[SunlitComet]

FSM says apply of bead of sealant but does not specify type. so best judgement.

 

[noJeepshere]

Maybe that's why I can't get my rear diff to stay sealed...

Last time I had it apart (replaced an axleshaft, bent the old one) I sealed the cover on with plain ol' RTV, then filled it up with Mobil1 synthetic gear lube, 75-90 weight iirc, with limited slip additive. Now it's leaking, again, and this is the third time it's started to leak, each time with Mobil1 and RTV.

 

[sparg93]

Maybe that's why I can't get my rear diff to stay sealed...

Last time I had it apart (replaced an axleshaft, bent the old one) I sealed the cover on with plain ol' RTV, then filled it up with Mobil1 synthetic gear lube, 75-90 weight iirc, with limited slip additive. Now it's leaking, again, and this is the third time it's started to leak, each time with Mobil1 and RTV.

Maybe!! At least for me i'm glad I came across that intel...synthetic lube can be really expensive and it's never fun for things to keep leaking!!

Just a side thought...if by chance its leaking out the same spot each time, maybe there's some warping??

---------- Post added at 12:36 PM ---------- Previous post was at 12:32 PM ----------

FSM says apply of bead of sealant but does not specify type. so best judgement.

hmm....

I'll need to dig further. I know for my front diff GL-5 is recommended, but I could only find GL-5 in synthetic. I think I'm going to head to the dealer and see what they say; but as we all know, sometimes the dealers know less then the forums!

 

[noJeepshere]

Maybe!! At least for me i'm glad I came across that intel...synthetic lube can be really expensive and it's never fun for things to keep leaking!!

Just a side thought...if by chance its leaking out the same spot each time, maybe there's some warping??

I'm not sure, the whole bottom of the diff is generally wet. I thought of that last time I had it apart and, as best I could considering, used a straight edge to check the housing and the cover. Both seemed fine. Right now it leaks at the rate of several liquid ounces a year, so it's not like it's pouring out. I'm not going to worry about it too much, if it suddenly goes crazy I'll fix it, but I'm doing the 14bsf swap in the future so no need to spend needlessly on this 10 bolt.

 

[sparg93]

I'm not sure, the whole bottom of the diff is generally wet. I thought of that last time I had it apart and, as best I could considering, used a straight edge to check the housing and the cover. Both seemed fine. Right now it leaks at the rate of several liquid ounces a year, so it's not like it's pouring out. I'm not going to worry about it too much, if it suddenly goes crazy I'll fix it, but I'm doing the 14bsf swap in the future so no need to spend needlessly on this 10 bolt.

For the 14bsf, do you plan on rebuilding it?

There's some misinformation on the web about which 14bsf will fit our rigs...from backing to backing plate, the 57" version will do!

 

[noJeepshere]

For the 14bsf, do you plan on rebuilding it?

There's some misinformation on the web about which 14bsf will fit our rigs...from backing to backing plate, the 57" version will do!

From the 88-93 light duty 3/4 ton pickups. Preferably later ones because they'll more likely have abs.

 

[SunlitComet]

just a correction fro me and update there are gaskets for the front and rear that should be used with some simple gasket sealer.

---------- Post added at 03:51 PM ---------- Previous post was at 03:48 PM ----------

rear--- RDS55028-1

front--- RDS55477- preformed no sealant needed.
by the way high end rear covers go o-ring so rtv leakage to worry about.

---------- Post added at 03:52 PM ---------- Previous post was at 03:51 PM ----------

the bad news that front one is $78. but worth it for a one time change out or rebuild.