What fluid for the rear end of an 01 GT?

MoatesGarage · Mar 1, 2006

I'm coming up on 60k miles here and that's when Haynes says to change the differential fluid. The only problem is I couldn't find what type to use. I'm assuming it's gear oil with a no-slip additive. Does anybody have any recommendations on what's best and what sucks?

Mike97gt · Mar 1, 2006

75-140 motorcraft synthetic (this stuff is expensive)

xl-3 fricton modifier. DO NOT let them sell you xl-7

thats what the stock stuff is and it works fine.

BLUE03GT · Mar 1, 2006

Royal Purple all the way

Kilgore Trout · Mar 1, 2006

Do not use 80-90 dyno oil, there is a little tag right on the dif cover that says exactly what svttech76 said, 75W-140 synth + four ounces of friction modifier.

Mike97gt · Mar 1, 2006

Kilgore Trout said:
Do not use 80-90 dyno oil, there is a little tag right on the dif cover that says exactly what svttech76 said, 75W-140 synth + four ounces of friction modifier.

One more thing i forgot, try to get away with as little of the modifier as you can, this will improve your traction out of the hole. What I like to do is slightly underfill the rear end ( a tiny bit underfilled so you can get another ounce or two in if needed of xl-3) Then I put in 2 ounces of friction modifier and go for a ride around the lot, if it chatters after a minute or so of driving at slow speeds I bring it back in and add another ounce. I repeat this process untill i get the chatter to stop, if needed fill the last ounce or so with 75-140. Most of them do need 4 ounces but do this if your tring to max out your traction on the stock limited slip.

Kilgore Trout · Mar 1, 2006

Interesting... Next time I am going to try that

timeless2 · Mar 1, 2006

svttech76 said:
One more thing i forgot, try to get away with as little of the modifier as you can, this will improve your traction out of the hole. What I like to do is slightly underfill the rear end ( a tiny bit underfilled so you can get another ounce or two in if needed of xl-3) Then I put in 2 ounces of friction modifier and go for a ride around the lot, if it chatters after a minute or so of driving at slow speeds I bring it back in and add another ounce. I repeat this process untill i get the chatter to stop, if needed fill the last ounce or so with 75-140. Most of them do need 4 ounces but do this if your tring to max out your traction on the stock limited slip.

Great tip, Mike!

Mike97gt · Mar 1, 2006

4u2nv said:
Great tip, Mike!

no problem

MoatesGarage · Mar 1, 2006

Yes, thanks very much for the tip...and the help.

cooter_11 · Mar 1, 2006

I know the Royal Purple diff. fluid already has the friction modifier in it, but I don't know if it will equal the amount svttech76 said to put in it. Since he knows what he is talkin about, go with his method. That royal purple stuff is expensive as hell too.

cooter_11 · Mar 1, 2006

FYI I run royal purple and have no problems, but his method might be cheaper.

MoatesGarage · Mar 1, 2006

Does it have to be the Xl-3? Or is it something I can get the equivalent of at an auto zone?

Mike97gt · Mar 2, 2006

well that royal puple stuff is very good. if you rather use that then that will be fine to. but if your going to use the stock fluid ( also very good stuff) then i recomend you try it this way.

if you look at a bottle of XL-3 modifier it has a spec number on the back. all auto fluids have these numbers. you can match that spec number up to another brand and have the same stuff

the98stang · Mar 2, 2006

Mobil 1 synthetic 75w-140 ....

SigmaPride · Mar 2, 2006

I have a '99 with 101k and my manual calls for 80-90 and says it doesn't need to be changed unless its leaking or submerged in water. However, I still want to change it and was wondering if at this point I should stick with the 80-90...assuming that is what Ford actually put in there as it has been changed before. Or if I could go to a synthetic with no problems.

Kilgore Trout · Mar 2, 2006

SigmaPride said:
I have a '99 with 101k and my manual calls for 80-90 and says it doesn't need to be changed unless its leaking or submerged in water. However, I still want to change it and was wondering if at this point I should stick with the 80-90...assuming that is what Ford actually put in there as it has been changed before. Or if I could go to a synthetic with no problems.

I think it does not hurt if you are over 30k or so really... Depends on how anal you are about these things. Since you are over 100k I think you should do it.

And the manual says both 80-90 and 75-140, but the tag on the diff cover bolts would preclude the manual. Do you have a tag?

To be honest once I drained my pumpkin I realized 80-90 was all I had so I had to go with it and have been running it for a year with no problems so far. But next time I will def go with what the tag says, 74W-140 synth.

Mike97gt · Mar 2, 2006

SigmaPride said:
I have a '99 with 101k and my manual calls for 80-90 and says it doesn't need to be changed unless its leaking or submerged in water. However, I still want to change it and was wondering if at this point I should stick with the 80-90...assuming that is what Ford actually put in there as it has been changed before. Or if I could go to a synthetic with no problems.

is your car a gt? you looked up the fluid for the 7.5 inch rear end used in the 6 cylinders

I am looking at the 1999 service manual right now and for the 8.8 rear end it calls for 75-140

kilgoretrout said:
To be honest once I drained my pumpkin I realized 80-90 was all I had so I had to go with it and have been running it for a year with no problems so far. But next time I will def go with what the tag says, 74W-140 synth.

thats going to destroy your limited slip clutches. all limited slip fords use the 75-140 with xl-3

Kilgore Trout · Mar 2, 2006

//adds track lock rebuild to "the list"

Mike97gt · Mar 2, 2006

just drain it and refill with 75-140 and see if the trac lok still works.

SigmaPride · Mar 2, 2006

svttech76 said:
is your car a gt? you looked up the fluid for the 7.5 inch rear end used in the 6 cylinders

I am looking at the 1999 service manual right now and for the 8.8 rear end it calls for 75-140

thats going to destroy your limited slip clutches. all limited slip fords use the 75-140 with xl-3

Interesting...I am looking in the Manual that came with my car(1999 GT) and it calls for Motorcraft SAE 80W90 Premium Rear Axle Lubricant for both the 7.5 and 8.8 inch axle(only difference is the capacity). I also know another guy with a '99 that runs 80-90 and he knows what he is doing. That is why I'm always confused about the 75-140 thing as I think it started in 2001 or so. My tag on the diff. doesn't say anything about the lubricant either.

Looks like it went from 80-90 to 75-140 in 2002 according to this chart: http://www.fcsdchemicalsandlubricants.com/supplier/quickref/axlelube.pdf

What fluid for the rear end of an 01 GT?

New Member

it doe snot

New Member

Fried or Broiled ?

it doe snot

Fried or Broiled ?

Vi Veri Veni Versum Vicus Vici

it doe snot

New Member

Member

Member

New Member

it doe snot

Active Member

New Member

Fried or Broiled ?

it doe snot

Fried or Broiled ?

it doe snot

New Member

Similar threads

Privacy & Transparency

Privacy & Transparency