I took a few minutes to search this forum before posting this.

As I've stated before, I bought my 97 Expy back in February and have been slowly doing all of the basic maintenance that I can on the truck as I can afford it. Now I'm considering changing the front and rear diff fluid before we get into the cold months. I have not noticed any vibrations, speaks, rattles, chirps, etc to be concerned about...I'm just trying to think long term with this vehicle as I'm a college student who refuses to buy a new vehicle once out of school (which is in less than a year! ). In addition, while I do know my Expy was previously in good hands, I don't have any repair bills or maintenance notes to go by. Thus the reason I'm trying to start fresh.

There seems to be various opinions when it comes to the fluid change. Some say don't do it unless it's been submerged; others have posted that they do theirs for good measure. That leaves me on the fence. With 111k on the odometer and no record of the fluid being change, what do you all suggest?

Specs:
Rear: 9.75", H6 code, 3.73 limited slip
Front: 8.8 -- I'm assuming LS as well? (Sorry Alloro, I know you told me but dumb me didn't make note of it)

If I should change the fluid here are my questions:
What weight is correct? Local parts guy said in his catalog the specs were 80w-90 but I read somewhere in my searching, someone else said 75-140 IIRC???

Does the front diff need the LS additive as well?

Do I need to seal the fill/drain plugs with, for example, loc-tite or pipe goop (I know that's not correct) to keep fluid from leaking or water from getting in?

Lastly, do I need to torque the rear pan bolts to a certain spec after letting the RTV seal?

 

i got my truck with 199xxx miles on it and changed mine with royal purple , i did the rear and my step dad did the front , i dont remember the weight off hand but 70-90 or 80-90 does sound familiar

 

From your owners manual; http://www.motorcraftservice.com/pub.../97exdog1e.pdf

REAR AXLE MAINTENANCE
The rear axle is filled with
synthetic lubricant and will not
require a lubricant change during
the life of the vehicle unless the
rear axle has been submerged in
water. In addition, rear axle
quantities are not to be checked or
changed unless a leak is suspected
or repair required.

 

looks like i waisted time and money

 

Unless the clutch packs start binding and grinding....

 

Well then, I guess that would make it a repair and not a maintenance issue.

 

I was told by my local Ford dealer to change the fluid at 30,000 miles becase they have had some problems with the dif going out. I have changed mine at 30,000 miles since maybe over kill but I feel better. These Fords are great trucks but are fluid sensitive meaning they like regular changes. I know there will be some body who will say they have driven 100,000 miles no problems, but I can tell you it would blow up on me. I have LSD in the rear and the front is open dif. I think the owners manual calls for 70w-140 synthetic for the rear with the additive for LSD. The front calls for 80w-90 no additive, I think I used 70w-90 synthetic in the front. I get my additive from the ford dealer its like 4 ozs. You should also plan on changing the trasfer case fluid some time before the snow flies. There are clutches in the transfer case for the automatic 4x4. When I changed mine last the fluid was burnt. I ended up using M1 trans fluid in it. I won't have to change it for another 10,000 miles but it is some thing that gets over looked.

 

Thank you for the good info. As far as the transfer case goes, can you direct me to any links here that covers changing the fluid? (I wouldn't think its too hard)

 

I know that there a some on here do a search to find them. Things to look for:
1. Loosen the top or filler plug first to make sure you can get it loose before draining.
2. Get some type of pump to pump the fluid into the transfer case, it is in a bad angle. Auto parts stores sell cheepies.
I use pipe dope on the threads of the plug. May not be needed but I do it any way.
I think using a synthetic trans fluid such as M1 will pay off. Not hard the only hard part is refilling so get a pump.

 

I just bought an '01 Exp XLT 4x4 and while I think I got a pretty good deal it has a few rough spots to clean up....nothing major, just some mild TLC. I was reading through the manual/service book to see what I should consider doing an specifically looked up axle fluid. Lifetime....I laughed out loud. I would never consider axle fluid lifetime, no matter what the manual says. Assuming mine has never been changed (113k) I can't wait to see what it looks like. Probably won't be too bad, I don't it's ever towed anything but I bet it's gonna stink. The front diff is open, not LS....there is no factory front LS in any of the light duty trucks is there?

I'll be doing both axles and the Tcase. I did the engine oil/filter today, some general cleaning and found a bit of cancer that I missed earlier. Next spring I'll be replacing the core support (assuming that's the nomenclature for it) but otherwise it's in pretty good shape.

I've got a list of stuff but since it's off topic I won't get into here. Suffice to say I would not consider axle fluids lifetime.

Cheers.

Jack Money
'01 XLT 5.4 4x4