How much Fluid? Rear diff 1999, D4

[Tackle]

Hello,

My rear differential is starting to leak on my 1999 XLT 4.0 sohc with axle code D4 (3.73 LS I think?). It's leaking from the bottom of the cover, so I'm going to replace the fluid and gasket. How much fluid do I need? I have 2 quarts of 75w140 synthetic and 4 ounces of the friction additive. Will I need another quart? Just fill it till it comes out of the fill hole, or does it need a certain amount?

 

[my pos mounty]

It will take all of both quarts and the modifier, plus some of a third quart.

 

[Tackle]

Alright, I'll go pick up another one. Just fill it till it doesn't take any more?

 

[my pos mounty]

yep, on a flat level surface

 

[ranger7ltr]

Mine took 5 quarts of synthetic Mobil 1...

plus the 4 oz. of friction modifier...Course when I pulled the cover I removed a lot less than that from the differential...


UPDATE: That should have been 5 PINTS plus the friction modifier...

I mistyped the title and did not put in 5 quarts...

And I used a gasket and rtv to seal up the rear cover...I got the gasket from Advanced Auto parts...

 

[Tackle]

Yea, I got just over two full quarts when I drained it. I'm letting the form a gasket set up right now. How long you think before I can add the oil? I won't drive it tonight, just would like it to get a little tacky before I dump it in. It's been a half hour or so.

 

[my pos mounty]

Mine took 5 quarts of Mobil1 synthetic...plus the 4 oz. of friction modifier...Course when I pulled the cover I removed a lot less than that from the differential...

Hmmm, are you sure about that?
According to the ford website, the capacity for our 8.8 rear diff is 2.9 - 3.1 liters, which is 5.5 to 5.8 pints. 2 pints per quart equals almost 3 quarts.
http://www.motorcraftservice.com/pubs/content/~WOXMNT/~MUS~LEN/42/99mntog1e.pdf
Scroll down to page 234 of 248 in the PDF document

 

[my pos mounty]

Yea, I got just over two full quarts when I drained it. I'm letting the form a gasket set up right now. How long you think before I can add the oil? I won't drive it tonight, just would like it to get a little tacky before I dump it in. It's been a half hour or so.

I waited just about 1/2 hour, filled it up and drove it away

 

[ranger7ltr]

UPDATE: That should have been 5 PINTS plus the friction modifier...

plus the 4 oz. of friction modifier...Course when I pulled the cover I removed a lot less than that from the differential...


UPDATE: That should have been 5 PINTS plus the friction modifier...

 

[colintrax]

I pored in 3 quarts plus about 6 oz of friction modifer and it was just below the hole, and I've left it there since. But I also completly wiped the inside clean, not one drop of oil in there when I put the cover on.