Year of truck, size of rear end might make a difference, but my 1997, 9.75" calls for 75W140 SYNTHETIC lube ONLY.....
There should be a tag on the rear end that will state what's required. Also, if you have a limited slip diff, you'll need a bottle of Fords Friction Modifier too...... I used Amsoil 75W140 that had the same spec # as Ford recommended and it said that it was good for LS diffs, but I paid $5.00 for the Ford stuff anyway and added it to the diff as well......
2013 F150 XLT 4x4 SuperCab EgoBoost Max Tow 3.73 gears OEM 20" wheels.
When changing the rear differential fluid, did any of you guys use a replacement gasket or did you just use gasket maker silicone? I think Ford just uses silicone but a replacement fiber gasket is available from Ford. Just curious. I have three quarts of Valvoline 75W-140 syn power fully synthetic ready to go. I also bought the 4 oz. bottle of friction modifier since I have an LS.
Pros are, it's a lot eaiser to clean off. Works just as well (once it sets and if you applyed it correctly). If you have the 9.75" rear end, it's hard to find gaskets for them (at least I could not find any).
Cons are, it involves a lot of extra time waiting for the stuff to set up and all, but I figure that's what BEER is for!! Helps if you have a garage to do the work in and you have other chores to do while you are waiting for the stuff to setup and don't need to drive the truck for awhile......
I use the red gasket maker stuff. Spread a bead on the cover, circling each of the holes and let it set for about 15 minutes. Put on diff and hand screw the bolts in a criss cross pattern to get even pressure on it and only tight enough to get the stuff to just squeeze out. If you torque it down at this point, it'll just squeeze the stuff out and you won't have any "gasket" when it sets up (personal experience with this one..... )
Let set for awhile (I usually wait an hour now) and then fill with lube. You can also tighten up the bolts a bit more at this point too.
After 24 hours, you should be able to torque the bolts down and you should be leak free until you take it off again. This is what I did the last time I had the cover off (had to replace an axle seal) and it's been leak free ever since.
So what weight oil goes in the Rear Diff? Because the Ford Spec # are different I assume that it's a different Viscosity.
But what is it?
Most likely 75W 140 Synthetic is required in your truck. Ford gets $20 a quart for this liquid gold - you'll need at least 3 quarts (one more for insurance if you're like me!). I used Royal Purple - ordered from Jeg's (although most on-line performance parts places can ship it). The local speed shop is a RP dealer, and said he couldn't get it! Best part was it was less than half the cost even after shipping.
I "ALWAYS" use a gasket on the differential.And,I can torque the bolts right there and then!And then fill it with fluid rite away too! It also gives me better piece of mind knowing I have the gasket there.Would you put an oil pan on without a gasket? How about valve covers? Timing cover?
Any good parts store that sells FelPro gaskets sell the differential gaskets.Here is the part number for the 8.8;
I've found myself having to learn a few things on my own about servicing my truck. How do I go about locating the differential under my truck to change the oil? If it's not serviced enough in that area, will it make wierd noises to let me know?
the differencial is the rear end of the truck, and if you really dont know what it is, its the round thingy under your truck that your rear wheels are mounted to. The middle round part is where all the rear end gears are located, its called a chunk or pumpkin. Thats where your fluid will be located.
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Join Date: Aug 2004
Vehicle: 1994 ford f-150
no offense, but if you dont know where your differential is, you should not be even thinking about messing with it. how are you going to know if it is limited slip? how are you going to know what grade of oil to use?
and another thing. the person above says he always uses a gasket. this person does not know that you can use rtv gasket maker.
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