Differental Fluid queston

[Billy177]

what is the fluid supposed to like when you look at it the fill plug was covered with shiny crap about the thickness of 3dimes stacked up and the fluid was about the same color. what does that stuff look like when it is new. i am not sure if it is original or not because there is that rtv sealant stuff on there instead of a gasket. i am going to change the fluid as soon as my gasket comes in the mail. is this bad or is this normal of fluid of a possible 75k on it

 

[Billy177]

this is the rear by the way i havent checked the front yet

 

[Alec]

Good diff fluid can last 100k miles if it stays clean. But shiny or milky means it has metal and/or water in it. New diff fluid has a slight sheen to it, but not as much as you're describing.

 

[Billy177]

this just means that i need new fluid and that it is not messed up. it is an open diff

 

[Alec]

The metal shavings aren't a good thing, but you'll probably be ok with just new fluid.

 

[Billy177]

also do i have to use the ford fluid or can i get some royal purple form jegs that is 75w-140

 

[410Fortune]

Billy,

80W-90 gear lube will work, no matter the brand.
However if you have the factory limited slip Ford recommends the friction modifier be added.

I personally swear by the Mobil synthetic gear lube.
Synthetci gear lube will run slightly cooler then conventional gear lube, it will also withstand higher heat and lubricate better. IN theory this would result in better gas mileage as well.

Now is also a good time to make sure your axle vent tube is not clogged, a clogged vent tube will not allow the hot fluid to expand and will put additional strain on the axle seals.........

 

[Billy177]

well the gasket came today and the fluid was not nearly as bad as i originallt thought it was a tad bit lighter than the color of the factory radio. i used some valvoline synthetic 75w90 it seemed to ride smoother and not require as much engine speed to move around at low speeds. now for the front i think i need a vaccum pump right.

 

[FIRE and ICE]

I did the front axle on my 92 a while ago and bought a suction gun from the local parts store ( looks like a large grease gun, but sucks in fluid one way and expels fluid the oposite way ).
I want to say it cost approx $20.00. I used it to suck out the old fluid and then cleaned it to pump the new fluid in. Just be VERY CAREFUL I once read a post where someone tried to use an extention hose and dropped it into the diff.
Mine went well with no complications.
Good luck

BTW: I believe that the filler plug at least on the rear is magnetic and that is why it had metal dust on it. Wish Ford would use it's "Better Idea" and make all the drain plugs magnetic --- couldn't hurt!