hang on for a few days, Ill send you the haynes manual I have along with the radio and cc plates..if I can find the manual today.

 

Its most likely just some oil that was on the housing from when you changed the fluid. Go back clean up the housing and then wait a day or two and see if its covered in fluid again.

 

Cool.

 

Yup, looks like it. I was just being overly cautious having never changed the fluid in a Mustang rear diff before. I cleaned it off with a rag and there was barely any fluid on it at all. Warmed the car up and drove it a few miles to the gas station, came back and it was still dry. I had a drip pan under the car from Sunday to today and there wasn't anything in it either, so it looks like it's all good!

Thanks everyone!

 

Well, here we go again..

It is indeed leaking, I got under the car for about 30 minutes the other day and poked around until I found exactly where it was leaking from. It it leaking on the bottom of the Diff cover, between the RTV and the cover.. The only explanation I can come up with is that the Pure synthetic is too light for the RTV and is leaking through the small gap when the silicone expands & contracts.. The pinion seal is NOT leaking.

I can't come up with any other answer than that, it just doesn't make sense. I managed to seal it up with some permatex spray, butthat's no good because it can't stand up to high temps. so what should I do? BTW, I did use Permatex Ultra Black and cleaned the **** out of the surfaces.

LRS sells a gasket for the 8.8, some recommend using a gasket + RTV on the cover.. Actually Haynes says: "Apply a thin layer of RTV sealant to the cover flange then press a new gasket into position on the cover. Make sure the bolt holes alight properly."

LRS Gasket

 

The rear end doesn't encounter high temps. We're talking only 200° tops. Also, the synthetic wouldn't be lighter, unless you used a lighter grade. Personally, I would take take the cover off and reapply the silicone. This time, apply it to the cover (and apply more of it) and wait an hour until you bolt it up. Then wait a day before you fill up the diff. This gives the silicone more time to cure. If you still have a problem, I'd be worried about something more serious, like a warped flange or cover.

 

Yep, you need to just take the cover off like he said and redo it again.

 

I use Royal Purple synthetic gear oil w/RTV(no gasket), and have no leaks.