ugahutch

Have 2004 FX4 with 151k miles. I have decided its time to change my rear end fluid, I have seen several variations on ways people have done it on here. Is there anyone with a similar truck that has done thing and can help me out. With correct fluids, RTV, and any additives if needed?

Horse

I replaced mine with amsoil synthetic and used a gasket when I reinstalled the cover. I haven't had any issues. And didn't need any friction grip additive.

rubbinsracin

when I changed my fluid i put Royal purple in because it was on sale and had a rebate. I also put in 2 bottles of ford's friction modifier. i wiped it down real good along the seal and put a little rtv bead on, then gasket, then another little bead of rtv, put the cover back on and snugged the bolts almost all the way finger tight, waited 20 minutes for the rtv to set up and then torqued em down to 29ft/lbs

barriosman

I think you are only suppose to use friction modifier if you have a limited slip differential. Double check me on this, but I am pretty sure.

07cruiser

Correct.