hey guys i was looking online dieselmanor.com found a ok deal on the cover,bolts/hardware, should i buy a diff gasket for the cover & axle sealant?
it says it has a groove in it for sealant, but should i use a gasket and sealant or a gasket, i'm confused? where can i get the proper gear oil besides the delaership?

 

I just did this three weeks ago on my 03. i also got my diff cover from diesel manor. I used high temp silicone gasket maker. I did not use any other gasket. when u pull the diff cover off u will see that is all ford used. As for gear oil, i used royal purple 75w-140. It has limited slip additive which we need for the rear ends. it took about 3 1/2 quarts to fill it up. after i drained the oil, i removed any of the old silicone from the pumpkin. Clean it up real good. I then put the gasket maker on the pumpkin and the cover. i used the whole tube. After i put the cover back on the truck i waited about an hour before i filled it up to let the silicone dry. It was real easy,, good luck.

 

One more thing, the oil needs to be synthetic and and 75w-140 for the rear diff.

 

i have 2 choices of oil mobil 1 75w-140, royal purple 75w-140 which one would save more in gas and keep the gears in better shape longer?

 

I did mine back in may I think just as described above, really easy mod. I dont think you will see a major increase in mileage if any at all, but I too used R.P 75-140 . have fun

 

what type and brand of gasket maker should i use for this app? ford or aftermarket gasket brand, which is better?

 

A friend and I did the mod at the same time. I bought the covers from the ford dealer for 40 dollars each and the stainless bolts and washers for both from the hardware store. Total in each truck was like 58 dollars. Since neither of our trucks had very many miles on them, under 10K we reused the oil and bought and extra quart of the ford 75-140 to make up for any thing we lost which was 0. We also used the ford sealant that they use on the diff cover and have had 0 leaks.

 

I got the black RTV from PepBoys, no issues with leaks.

 

I used black rtv from pep boys too.

 

I did this last year and also had the cover polished. Refilled with royal purple 75w-140 and used "the right stuff" gasket maker to seal it and it works great.

 

hey guys got all the necessary parts in today diffcover, oil and permetex ultrablack rtv sealant, on the sealant it says to hand tighten the bolts until the stuff begins to squeez out around the flange then tighten about a hr later is this how you guys did it or shouldyou just tighten down to diff cover bolts until they are tight? (this is my first time doing this i dont want to f... it up sorry.)

 

btw i am going to use royal purple 75w-140 oil hope it is better than the stock stuff.

 

Just because I am curious...why would you change out the diff cover?

 

Because the 08 is aluminum and has cooling fins for you guys that do a lot of hauling, and it looks cool.

 

I tighten the bolts in a star pattern and did not wait and hour to retighten them. I was a little worried because i read somewhere that they needed to be torqued. I hand tighten as hard as i could and have had no leaks. Grab a beer and climb under that truck. Good luck