I just changed the fluid in my front diff and it's leaking a little bit out of the bottom corner. It's been a few days since I did it and I retightened it yesterday and the bolts were surprisingly loose, obviously the gasket settled down. I have to check if it's still leaking when I get home later, but if it is, can I put some rtv on the outside? And what's the deal with all the types of the permatex rtv. What color should be used?

 

Don't use a gasket. Get your self some RTV and make sure both the cover and the diff housing are spotless. Use break cleaner to get all the oil off the surfaces, put a good healthy bead of RTV on the cover ( I use black) and bolt it back on tight. I then let it sit and cure for an hour or so and then fill and go. i just did my D30 in my 89 last week with temps in the high teens in my garage and not a leak. Your going to have to pull the cover and start over. Putting RTV on the outside where it's leaking won't work, that area is contaminated with oil that will keep seeping out and just go through the RTV.

 

can I catch and reuse the oil? It's Mobil 1 and it was $10 a quart

 

I wouldn't. but I guess if you have a real good way to filter it out I guess you could but I'd just put new in again and chalk it up to lesson learned.