Black or Ultra Blue? Going to do the rear differential. The ultra states rear differential on there site the black doesnt. But I here alot of people use the black. I have some black in the garage will it work or should I drive to the store and get the ultra blue?

 

use the black

 

Black is supposed to be oil resistant I think

 

Did you mean Ultra Black, or just Black? The black's are normally for repairing weatherstripping and the like, so stay away from those in this case.

Both are highly oil reisistant as well as sensor safe.

The red is for continous high temp use, not sensor safe, and not as oil resistant as the Ultra's.

I believe the difference between Ultra Black and Ultra Blue is that Ultra Blue is supposed to work better to bond to surfaces that are not completely clean of oil.

I've used both, as well as the red over the years for all sorts of gasket making and never had an isssue with leaks.

As long as you clean the flanges really well, use either one.

 

Well since I had to run to get the oil anyway, I went and picked up the Ultra Blue. So far no leaks. I'll give it a few days to make sure, then I'll be worry free. Found a wire brush works better than a scraper to clean the surfaces. Tried a gasket remover but it didn't penetrate that well or it was just to old from being in the garage. Thing took almost 3 full quarts instead of the 2.45 it states in the Haynes Book. But money well spent since it still cost me about half. Alot of places wanted $100-$120

 

I used this stuff I get from work and it will eat through a gasket or paint in no time. Just dont get it on any skin and it WILL burn

 

I have always used the blue and being ****...along with a gasket. Never a leak on any of my vehicles. And use the stuff Weed shows works great with minimal effort of a brush.

 

Yep, I used to have some of that but I think autozone either was out or they don't carry it. Napa I know does for a fact but I didn't want to drive to get there. But for future reference the 3m stuff sucks big time. It's says silicone on the can but it didn't peneatrate the RTV at all.

 

Black or ultra black on the rearend.

 

I haven't used it in automotive use yet, but Hylomar UniversalBlue is what I use to seal mating surfaces on cooling pumps for power transformers in the power utility industry.