My rear diff is leaking fluid and i would like the change the cover to this one.

http://store.summitracing.com/partdetail.asp?autofilter=1&part=TFS%2D8510200&N=700+4294891995+4294785122+115&autoview=sku


What is the best rear diff fluid to use for a used 12 bolt rear with richmond 373s and an eaton posi?

do i fill it from the tube with the plastic cap on it or is that the vent?

anything else i will need to do with this cover? I saw that there are two bolts that go into the diff for more support. is there a right way to put those in or do i just screw them in?

thanks all

The cover will come with instructions about using the preload bolts. Be sure to use some sealant around the jam nuts or you will have an oil leak.

There is a pipe plug on the right side of the rear end in the center casting in front of the right axle tube. It might be covered with grease and dirt, but it is there. This is the ONLY correct place to add oil. Fill it until the oil just starts to run out this hole. If you fill it from any other place then the oil level will be wrong.

Any 80W90 GL4 or GL5 gear oil will work. Use a bottle of GM or Ford limited slip oil additive. Don't use any other brand.

thanks for your responce, should i use sealant around the whole thing or just the jam nuts. Oh and sorry to be a novice, but which are the jam nuts?

is it okay to use synthetic gear oil? or will that be too thin for my application?

I use Amsoil 75W90 Severe Gear synthetic oil in most of the rear ends that I build. I haven't had any problems with it. The preload bolts will have jam nuts on them. Oil will leak through the threads of the preload bolts. I use some sealant behind the jam nuts to keep the oil from leaking out. It seems to work pretty well.

okay, thank you i was thinking either royle purple or amsoil. i'm sure ill understand where to put the sealant when the stuff arrives.