Change differential fluid???

[swshawaii]

Using the fill plug level, the differential will be overfilled if the rear is elevated.

Also very important to loosen the fill plug BEFORE removing the 8.8 cover.

 

[Mounty99]

Using the fill plug level, the differential will be overfilled if the rear is elevated. Also very important to loosen the fill plug BEFORE removing the 8.8 cover.

Ok, good to know. Was thinking a little extra fluid might be a good thing. Thanks for your help.

 

[swshawaii]

In this case more is not better. In fact, remove your axle vent tube to make sure it's clear, otherwise you could blow out axle seals. Don't know if you've seen the Amsoil "white paper" tests on differential fluids. I'm using only one Amsoil product in my ST, and it's Severe Gear. Many will say the testing is biased, even though it's from an independent lab. Knowing it will be in there for so long is peace of mind to me. Remember to add friction modifier before filling if you have a limited slip differential, preferably Motorcraft XL-3. The FM additive mixed in with many gear lubes is not adequate to stop chatter.

http://www.syntheticwarehouse.com/brochures/g2457_gearlube_study.pdf

 

[SoNic67]

That's a cool link...
I did already argue with someone that the XL-3 might be needed even if the gear lube is advertised as "LS".
However, note that the rear LS fluid is 75W140.
For those numbers is synthetic only...

 

[bluestream1]

That's a cool link...
I did already argue with someone that the XL-3 might be needed even if the gear lube is advertised as "LS".
However, note that the rear LS fluid is 75W140.
For those numbers is synthetic only...

Ford has changed the gear oil recommendation for rear axel to 75W140 for all 8.8 axels whether they are LS or not. You defiantly want that fluid weight in an older axel.

You can get conventional oil in 75W140. Your choice as to what you want to spend.

 

[SoNic67]

I would never trust a 75W140 conventional (newer saw one). Is too "wide" range, it would require a lot of additives in a conventional, and I know how long those additives can last.
Plus Ford requires synthetic on rear. They must know something.

 

[bobflood]

Couple of things to reinforce:

- Make SURE you can get the rear diff fill plug out (it's either a 3/8 or 1/2 square drive hole) BEFORE you pull rear cover to drain fluid.

- If you change the diff fluid, use this opportunity to pull the rear axles and service your parking brake shoes. They are a total PITA to do with the axle in; a breeze with the axle out.

Good luck.

 

[bluestream1]

I would never trust a 75W140 conventional (newer saw one). Is too "wide" range, it would require a lot of additives in a conventional, and I know how long those additives can last.
Plus Ford requires synthetic on rear. They must know something.

I meant 85W140 conventional (typo) and its a good quality oil. I wouldn’t worry about VII in the oil as its 1000x better that what the OP has in there now. This weight gear oil is often used in heavy truck and equipment.

Here are some specs:
http://lubricants.petro-canada.ca/resource/download.aspx?type=TechData&iproduct=1068&language=en

TRAXON 85W-140 is formulated to meet Dana,
ArvinMeritor, ZF, Navistar, and Eaton’s stringent
GL-5/MIL-PRF-2105E gear oil specifications
(see specific OEM requirements for further
details). TRAXON 85W-140 is approved for
Mack Truck differentials where a Mack GO-J oil
or MIL-PRF-2105E oil is specified. TRAXON
85W-140 is listed by ZF as approved for
classes 05A, 07A, 16D and 17B.

With 193K on that axle, how much longer do you think it can last? Synthetic may be overkill price wise. Your doing more than most people by just changing it.

OP's axle may have come with conventional oil as, we have not heard the ratio or if its a LSD. The 140 will run about 20 degrees hotter and lower MPG a bit, but with those miles on it theres no other choice.

 

[bluestream1]

The FM additive mixed in with many gear lubes is not adequate to stop chatter.

http://www.syntheticwarehouse.com/brochures/g2457_gearlube_study.pdf

LSD additive has no lubricating properties, so you want to keep the amount to the absolute minimum.

I have two LSD vehicles using Redline with the additive in, and have zero chatter.

 

[Mounty99]

Well, didn't get my Amsoil order in, so couldn't get to the diffs this weekend. On the Amsoil, any reason NOT to go with Severe Gear over the Long Life? Or for the transfer case, Signature series over the OE multi-vehicle??

LSD additive has no lubricating properties, so you want to keep the amount to the absolute minimum.

I've read that Severe Gear already has some LSD additive in it. Should I still add the full 4 ounces of Motorcraft XL-3 to the rear?

 

[bluestream1]

One more thing. Looks like people jack up front to help with draining. Does anyone then jack up the back when filling to help put a little extra fluid back in? :scratch:

are you talking about jacking up the back to over fill the differential? If so, that will under fill it as the fill plug is on the front of the diff. The correct level is 1/2 inch below the fill plug, if you want to overfill, fill until it comes out the fill plug.

 

[swshawaii]

I've read that Severe Gear already has some LSD additive in it. Should I still add the full 4 ounces of Motorcraft XL-3 to the rear?

Your call. I've read many with LS differentials using aftermarket gear lubes containing the additive and still had chatter.
Severe Gear is Amsoil's best. Also read that the only friction modifier that worked for them was the Motorcraft XL-3.

NOTE: AMSOIL Synthetic Gear Lubes do not require the use of this additive. However, not all differentials respond the same and if chatter is noticed, the addition of AMSOIL Slip Lock will eliminate it. For chattering differentials not running AMSOIL Gear Lube, this product is an excellent solution to the problem.

 

[bill06447]

I was under my truck today replacing rear shocks, and noticed a tag bolted to the rear pumpkin- "75w140 synthetic lube ONLY" on the opposite side is the tag with date code, ratio, etc.

Bill

 

[bluestream1]

I was under my truck today replacing rear shocks, and noticed a tag bolted to the rear pumpkin- "75w140 synthetic lube ONLY" on the opposite side is the tag with date code, ratio, etc.

Bill

Good news for you. Other axles with different ratios may have been filled with different fluid. However a 140 weight will never be wrong in an old worn axle

 

[bluestream1]

Well, didn't get my Amsoil order in, so couldn't get to the diffs this weekend. On the Amsoil, any reason NOT to go with Severe Gear over the Long Life? Or for the transfer case, Signature series over the OE multi-vehicle??


I've read that Severe Gear already has some LSD additive in it. Should I still add the full 4 ounces of Motorcraft XL-3 to the rear?

NO!! If you still have chatter (i doubt you will) add one ounce at a time until the chatter is gone. More is not better with LSD additive, as it does no lubricating...

I think I said that already...

 

[SoNic67]

As a side note:

I added the Motorcraft XL-3 friction modifier in my Sable transmission and it cured al
most completely the torque converter judder. Previously I did replace the fluid in the pan.

 

[Mounty99]

Ok, so FINALLY changed the front diff, rear diff, and transfer case fluid. Now running Amsoil severe gear in the diffs and signature series in the transfer case. Added only 1/2 bottle of the friction modifier to the rear and everything is running perfectly. Also, changed the transmission fluid with motorcraft, and it's shifting like brand new.

Thanks again for all the great advice. The Merc just passed 202,000 miles and is running great! So glad I listened to you guys (and not Ford)! Best wishes...

Bill

 

[Fpo]

Ok, so FINALLY changed the front diff, rear diff, and transfer case fluid. Now running Amsoil severe gear in the diffs and signature series in the transfer case. Added only 1/2 bottle of the friction modifier to the rear and everything is running perfectly. Also, changed the transmission fluid with motorcraft, and it's shifting like brand new.

Thanks again for all the great advice. The Merc just passed 202,000 miles and is running great! So glad I listened to you guys (and not Ford)! Best wishes...

Bill

Let me know how you like the AMSOIL products. You may notice slightly better fuel economy too!

 

[drdoom]

As a side note:

I added the Motorcraft XL-3 friction modifier in my Sable transmission and it cured al
most completely the torque converter judder. Previously I did replace the fluid in the pan.

Nic I've never heard of that additive, but of course my Taurus shuddered. I put some LubeGard in after servicing the transmission, it seems OK now.

 

[SoNic67]

Nic I've never heard of that additive, but of course my Taurus shuddered. I put some LubeGard in after servicing the transmission, it seems OK now.

This one: http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=1WZ35K01H33P6R64B57M ?

Is still a friction modifier.