MTFCA Forum

I recently sealed up my differential with Permatex Gear Oil Gasket Maker. I did a little experiment at the same time, applying some between two pieces of aluminum sheet metal and clamping them together. The sealant is supposed to cure in 24 hours but the fine print says it may take longer under cold and dry conditions.

I don't leave the heat on in my tiny shop when I'm not working out there and the interior temp will drop into the 40's. Checking my experiment I found that after 30 hours it was still not set up. I decided to leave the heat on overnight and the next day it was cured.

I'm sharing this information just in case some of you in the great white north are doing something similar so that you know that a full cure of the gasket maker will take longer at cold temperatures.

I've always used Ultra Grey for axles, or Mopar gear oil sealer, which was grey also (looks like the same stuff). I had a surplus of that from my dealership days. I like to let it set up before filling.
I used the Mopar stuff to seal a 3/4" wide inward rib with a crack in it, on my motor home holding tank...16 years later and still holding poo !!

Is that stuff Grey or black ?

Gray - it has a little different consistency than your normal RTV. Cleans up really well with a little brake cleaner on a towell.

RTV: Room-Temperature-Vulcanizing.

Would this be good for the hogs head ? I have been using the gray and the black and it still wants to leak. What does everyone else use ?

According to the pkg, this sealant is designed to be used in a "gear oil" situation. Gear oil tends to break down RTV and the gear oil is to be used where gear oil is present.
This document tells it all. With RTV I had a pretty good seal with slight leakage. With Gear Oil Gasket Maker I have had zero leakage.
https://441py33rout1ptjxn2lupv31-wpengi ... /81182.pdf