What is the difference between Mack White silicone and Black and Red?

[Anne Bocchini Kirsch]

I am putting on a timing cover and it was sealed with white silicone, which I have only seen in Mack tubes. I have a tube of black and a tube of red but no white. I think the dealer sent the black when I asked about the timing cover but I can't remember. I know they didn't send white. Anyone know what the difference is? Does it even matter?

[Dirtymilkman]

I use Mack grey silicone for everything. That stuff is amazing. Even on the three piece exhaust manifolds, it seals them right up. I never saw any other colors

[Anne Bocchini Kirsch]

Exhaust manifolds? Wow. I'd never heard of using it on exhaust actually until today, someone mentioned using the 750 degree copper stuff for exhaust manifolds when I was searching for the difference between silicone types, but I'm surprised to hear it works. I've always used muffler weld type stuff for stubborn exhaust issues that nothing else seems to take care of, but it does get brittle so it only lasts for a year or so. I'll have to try it. I'd never seen Mack grey before, just the white, black and red. I'm guessing the grey is like the high-torque grey permatex. I thought permatex made everything, but I've never ever seen white until I found an old tube of Mack white last year on our parts shelf (I used it for an axle gasket and it worked) and then the old white on my timing cover. Permatex doesn't make a white and so far as I can tell Mack is the only company that does which led me to wonder what exactly is it (on a Sunday, of course).

[MACKS]

The Mack white silicone is tough stuff, I know they used to recommend using it on the covers off the air to air charge air coolers on the older trucks,thats the only time I used it.

[e9500v8]

The white is made by Dow Corning I have the number in the shop