I just got my 05 F150 serviced at Ford today. They stated that my differential and transfer case fluids needed to be changed. I was quoted 97.00 for the transfer case change and 150 for the diff. fluid change. I thought that was a bit on the steep priced side. I went to http://www.f150store.com and ordered a new rear diff. cover P/N 336-911 for the same price as the quoted change. I figured for the same price as getting it done at Ford I could do it my self while upgrading the diff. cover.

My question is what all do I need to do change out my front and rear diff. fluid. I am not to worried about changing the transfer case fluid as there is a drain plug and a fill plug. What are the steps in performing the front and rear diff. fluid and what equipment is needed? Should I add friction additive to the diff. oil and if so what type is recommended.

Thanks All for your help.

 

How many miles do you have that they are telling you this? You should be good for 100K. Diffs are easy, just loosen the covers and drain into a pan. If you have limited slip, then yes you need to add the modifier. Your owners manual will tell you the specs, but it's synthetic lube. I plan on going to with Royal Purple when I change my out this spring.

 

I have 31,000 on the truck. Is there a need fo a gasket for the covers or Blue RTV silicone on the matting sufaces?

 

31,000 miles?? That's low to be changing diff fluids? Unless the axles were submerged? Is the fluid milky? Just curious. RTV still works for the covers...

 

They said the rear diff/ fluid looked burnt. Blackish in color.

 

jjed,

I changed out mine when I replaced the rear axle seals. Super easy to do.

Take out all but the top bolt from the diff cover. Loosen the top bold and carefully pry up on the cover to break the seal to let the fluid drain. use something wide and flat, not a screwdriver. Once the fluid has drained out, you can remove the last bolt to remove the cover. The factory cover uses sillicon to seal it, so you will have to clean it all off and re-apply a new bead. Have a look at the way the sealant was run by Ford originally to get the proper pattern so it seals properly.

I installed a Mag-Hytec cover on mine when I was doing the seals, which has a rubber O-ring seal, drain plug and dipstick, which are some nice features, plus it increases the oil capacity. I also went with Royal Purple oil, no friction modifier needed.

Good Luck.

 

I located the rear diff. oil that is called for in the manual -Motorcraft SAE 75W-150, Ford part #XY-75W150-QL with 4oz. of XL-3. However I need help locating the fronts. The front states Motorcraft SAE 75W-90, ford part #XY75W90-QFEHP. I seem to not be able to locate while searching the internet. Also is the XL-3 friction additive neccessary in the front diff.?

 

No, it is only needed in the rear if you have a limited slip.

 

Thanks. Do I put the same oil in the front as in the rear?

 

If I remember right, the rear is synthetic and the front is conventional. I don't think it matters, but I haven't done any research into the differences or why it is this way. I plan on doing my front this summer and going with the Royal Pruple Max-Gear. I used Max-Gear 75W140 which as the friction modifier already in it when I did the rear.

From the Royal Purple site: "Max-Gear is recommended for use in truck, motor home / RV, and automotive front or rear differentials, manual transmissions, and lower gear units of marine engines that specify use of an API GL-5 or GL-4 fluid. All viscosities of Max-Gear are formulated with hypoid friction modifiers necessary for use in clutch or cone type differentials. No additional additives are necessary."

Doug

 

At 31K miles is way to early. I would wait until at least 60K under normal driving. And as far as the dealer telling u its burnt and black. How would they know. its a sealed unit. They would have to remove the cover to see that. They just wanted to make a sale.