96 Vision TSI (LH) - Differential Fluid?

While changing the transmission fluid and filter (I used Mopar filter,
ATF+4, and re-usable gasket) on my 1996 Eagle Vision TSI (3.5L, 64K miles)
this weekend, I noticed that it has a front axle differential. The fill
plug was labeled 80-90W gear lube and there appeared to be a drain plug at
the bottom. I guess I should not have been surprised by this since it has a
longitudinal engine, but admit that I had assumed the design was similar to
our transverse engine minivan where the transaxle is lubricated by the
transmission fluid.

I really don't recall hearing much in this newsgroup about changing the gear
lube in the differential for the LH vehicle. Is the differential gear lube
fluid used from the manufacturer supposedly good for the life of the
vehicle? If not, what is the recommended change interval (years or miles)?
I'm thinking of changing it this next weekend, but wondered if anyone could
offer advice based on their experience.

Specifically, will running the vehicle beforehand and then opening the fill
plug help the fluid drain quicker? Is any particular brand of non-Mopar
gear lube recommended or is there any brand to specifically be avoided?
What is the capacity (I am guessing from the differential size it holds
about a quart)? As with old rear end differentials, do you fill to the
bottom of the fill hole? What is the best way to fill given the awkward
fill hole location?

Thanks in advance for advice. The job looks simple enough, but I figured it
won't hurt to get pointers from someone who has done this before.

Bob

 

Bob Shuman wrote:

Draining shouldn't be too bad so long as the fluid is warmer than 50
degrees F. Check the owners manual for recommended lubricant, IIRC it is
very adamant about NOT using synthetic hypoid oil and using ONLY the
recommended weight (80w90, I think).

I always use a suction gun to drain and then also re-fill my RWD cars'
differentials, and I use it to fill this one as well. The drain plug is
a nice touch- saves having to rinse the suction gun in the parts washer
before putting clean fluid in it.

 

Don't feel bad - I had a dealer tech argue with me that my Concorde
didn't have separate fluid for tranny and diff. I asked where their FSM
was, and when they handed it to me, I turned to one of the pages that
spelled it all out.

According to my '99 FSM: If you go by Maintenance Schedule A (normal
service), then yes. If you go by Schedule B (severe service), it should
be changed every 15k miles. I'm in favor of something closer to
Schedule B regardless.

In reality, every 25k miles or so should be adequate for anything but
truly severe driving conditions.

Of course. Any time a fluid is warmer, it wil flow faster and more
thoroughly.

If it's the same diff and tranny as in the 2nd gen LH vehicles (and I
think it is), it takes just under a quart of gear oil (stated in the FSM
as 0.95L/1 qt. - just under a qt. on mine started running out of the
fill hole). But - yes - fill to bottom of fill hole.

If I'm not mistaken, the drain plug has a square hole for a 3/8" ratchet
drive or breaker bar.

I used a funnel and a plastic tube to put fresh fluid back in my '99.
No surprises except the FSM said to use only 75W-90 oil, and there was a
tag attached to the fill plug that said to not use anything except
80W-90 like your. FSM probably sayas 75W-90 so they can squeeze another
fraction of a percent out of the fuel mileage numbers for CAFE. In
ambiguous situations like that, I always go with the thicker option
since I figure the mafgrs. tend to push things to thinner for their own
benefit (again, CAFE being a higher priority than longevity for them).

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")

 

Because you have a longitudinal engine your differential has hypoid gears..
you can't lube hypoid gears with ATF shear strength is just too low.... Well
suppose you could if you didn't care how long they lasted.

Ted

 

Ted & Bill & Steve,

Thanks for the input. With 64K, I guess its about time to change the old
stuff out. I'll pick up a quart of Valvoline 80-90W gear lube and have at
it in the near future.

Bob

 

There is no recommended change interval, even in the Severe Service (B)
intervals, unless vehicle is in police, taxi or delivery service, in
which case differential fluid replacement is specified every 15,000
miles. You remove the fill plug, then the drain plug. Replace drain
plug and refill it to the bottom of the fill hole. Getting it hot will
help the old fluid drain faster and take more contaminants out with it.