Differential Cover Gasket...Necesary? or just use sealer?


New Member
Hello everyone..I am about to change my rear end gear oil.

I have everything I need...with the exception of the gasket for the rear end cover.

Do you think it would be ok to simply use RTV Sealer as opposed to a gasket?

It seems they are not available anywhere..even the dealer told me I'd have to wait to get one...I am simply trying to get this done and over with .

Thank you for your help!


New Member
RTV is fine. I use Ultra Black. Just make sure to circle around all of the bolt holes as well. And make sure both surfaces are flat and clear of any previous gasket or sealer. You can put the RTV on the differential itself or on the cover, let the RTV kinda form a skin over itself over for about ten minutes or so before installing. Then tighten in a star pattern.


New Member
By the way what kind of gear oil is recommended?

My 2000 V6 manual convertible has an 8.8 from Factory
not a 7.5


New Member
I have a 2000 V6 manual with an 8.8 ( from factory)

Do you guys think I can get away with 80W 90 non synthetic?


New Member
Get underneath the car and read the tag on the diff. The 99-04 V6s use the same axles as the GT's 8.8 so it'll probably look close.

It will look similar to this



New Member
Yeah thanks for the Tip

My tag read 260 A I
3 27 75 9J 27

So Obviously I was confused

I am assuming this means 3.27 Gears..... which is what I thought it had along
and the 75 must mean it is 7.5 rear end

I was going by this.......http://www.mylrs.com/blogs/lrs/archive/2009/04/24/mustang-7-5-amp-8-8-rear-axle-info.aspx

When you look at the bottom picture ... that pumpkin is supposed to be the 8.8.

Both the pumpkins on my Stangs have this...... my 93 5.0 and my 2000 V6.
This is what created my confusion to begin with.

Regardless of the info I found online... the 7.5 and the8.8 look extremely similar from the outside. Some sites explain that the covers have slight differences ......but not so at least in my case the covers are identical!

the one thing that still set my V8 axle appart from my V6 is the quad shock supports

The V8 has them the V6 does not!

Thanks for the tips greatly appreciated!!


New Member
I have done rear covers with a gasket, and with just RTV, and been successful both ways.

IMO, a careful installation is the key to being leak-free here.....stuff like making sure sealing surfaces are super-clean, sealer applied evenly, bolts tightened properly. :thumbup:

The 7.5 and 8.8 look very much alike, it can be hard to tell them apart without them sitting side-by-side to compare.


Teh TC6!
For anything where a gasket is available, it is worth the wait to get. The tranny shop that put in my T-Lock only used sealant. I found out actually just last week because it had sat for a bit and there was a puddle of oil under the rear. I look under and see it leaking from the cover. I open it up and find nothing but sealant.

If you are going to use sealant, it had better be a perfect job. You should be able to find a gasket at any parts store, if not in stock they can overnight it surely. Use that and sealant to hold it in place, and you wont have to worry about it period until next oil change.


Well-Known Member
Dark, idk what ur guys did wrong but i took off my diff cover to inspect why my rear was ticking, i didnt buy a gasket. I bought the sealant, and made sure to apply it well and follow directions to let it set a bit before tightening it all the way then tighten down. I havent had any leaks yet so im not worried. Havent even shown any signs of leaks.


Teh TC6!
The leaking came about ~25,000 miles after the work was done. A gasket will last at least the recommended 60,000 mile oil change interval. Sealant, especially under constant contact with oil will break down. The gasket is one more barrier of protection that I still fail to see why_anyone_would bother to overlook. There's zero reason not to use one.


what kind of gear oil for the 7.5 rear and do you have to add an additive to the rear even tho it's not posi?