Ford Limited Slip Differential Oil Change

[Oldwolf]

I need to replace the oil in my LS differential on my 2002 Ford Explorer.

The manual says to add one bottle (4 oz) of friction modifier XL-3 to the new fluid which should be about 1.5 pints.

I plan to use Mobil 1 75W-140, the weight Ford recommends, and probably the CRC branded Friction modifier that does meet the Ford specification shown below (Available at AutoZone).

Anyone else used the CRC product or should I pick up a bottle of the Ford product? Any other comments are welcome too.

Quote:

All rear axles are filled with Motorcraft SAE 75W-140 High Performance Synthetic Rear Axle Lubricant, part number XY—75W140–QL or equivalent meeting Ford Specification WSL-M2C192–A.

Limited Slip differentials must add 118ml (4 oz) of Additive Friction Modifier XL—3 or equivalent meeting Ford Specification EST-M2C118–A to the rear axle whenever the axle has been serviced.



Thanks.

 

[Johnny]

Before you go adding extra additives, check with Mobil first as I believe their 75W-140 already has the LS additive in it. According to their PDS is already has the additive. I would not add additional additive.

http://www.mobil.com/USA-English/Lubes/PDS/GLXXENPVLMoMobil1_Synthetic_Gear_Lubricant_LS_75W-140.asp

 

[Oldwolf]

I sent them a question asking this. I'll post the reply. Thanks.

 

[Johnny]

I will say that I've never had to add any LS additive when using either the Mobil 1 75W-90 or 75W-140 product in any Ford or GM LS application.

Change the diff oil and find a large empty parking lot and do about 4 or 5 large figure 8's, and away you go.

By the way, the Mobil 1 75W-140 is a very good product.

 

[SuperDave456]

I agree with the previous post.
That being said if you hear a knocking noise from your rear diff after the fluid change you need additional anti-slip additive.

I changed out the fluid on my '98 F-150 and it required 75w140, I used amsoil, and even though it had the slip additive in there I added the amsoil brand "Slip-Lock". I haven't had chatter and it seems to work just fine.

I also added the product you speak of (the stuff autozone sells) to a Bus that belongs to a friend. He uses the bus for a Homeless ministry. However, I used Rotella 80w90 (dino) that I picked up on sale. The Rotella required a slip additive. I have not heard any complaints out of him about any chattering either.
He packs that bus with 15+ people, crates of donated food, water bottles, and its less aerodynamic than a Humvee. If it was going to give an issue he would have it.

 

[Johnny]

SuperDave, did you have to add the Slip-Lock or did you just do it for your own satisfaction? Good for your friend, thanks for helping him.

 

[DieselTech]

We do roughly 10-15 diff services a week. If the application requires LS additive it gets it. We only use Amsoil or Redline diff fluid. For my shop it's better to not have a customer ever need to worry about chatter and I don't have returning customers with chatter issues. Fords get Redline 75-140 and 1 bottle of redline LS additive. In 5 years of being open I have never had a return for chatter.

 

[Johnny]

DieselTech, any reason you use Red Line in Ford's instead of the Amsoil gear oil?

 

[DieselTech]

I have only 75-110 left of Amsoil, then I will use redline exclusively. It gets delivered to the shop locally for less and I believe redline is a superior product.

I would say 75% of my customers use their truck to hotshot, so the extended intervals of amsoil are good. I noticed most want it changed at 50K anyway.

Redline delivered for 7.52 a qt is tough to beat!!

 

[Johnny]

That's a very good price on the Red Line gear oil.

 

[SuperDave456]

Originally Posted By: Johnny
SuperDave, did you have to add the Slip-Lock or did you just do it for your own satisfaction? Good for your friend, thanks for helping him.


I added Slip-Lock to my truck just for my own satisfaction. I bought it and decided to add it to the mix before testing the new fluid by itself in the differential. I was under that truck and I didn't want to do that smelly job again if I did have an issue. Adding the slip-lock is easier than adding the 75w140, its only around 4oz, and although I don't know if it was needed it is a Amsoil product so I know I am good for quite some time.

I don't drive my truck much I have no idea how long it will take me to accumulate another 100,000 miles. But at least I know the rear differential is good for that long.

 

[DieselTech]

Keep in mind johnny my orders are fairly large with gear oil 75-90,75-140,additive,5-30,5-20,and 15-40.

Yes the local redline folks take pretty good care of me. They have never been pushy and drop in pretty often to just hangout and take more of an interest then slinging oils.

 

[Johnny]

Diesel, what part of AZ are you in? Does your shop have a website?

 

[jstutz]

I can not speak about your ford, but i have some experience with my 01 blazer that is related to the topic. When bought new, it had a shuddering as you would corner hard, out of driveways or in parking lots. I took it back to GM and there solution and explanation was this. The truck has a LS diff in it and from the factory was filled with valvoline dino 80w90. He said some trucks that have the LS a little tight will chatter like this and it is normal. He added GM friction modifier and it was smooth as glass. Upon my 15k mile service, i changed it to M1 75w90 with no extra friction modifier and it remained smooth. I have been using the M1 since and change it about every 30K and have never experienced this shudder again from the diff. M1 claims that they have the LS additive and from my experience i believe them.

 

[Oldwolf]

Here are the two products CRC offers.

Both meet Ford specifications. The 4 oz bottle is the volume needed.

Trans-X® Posi Trac® Limited Slip Gear Oil Additive, 7 Fl Oz

Equa-Torque® Differential Friction Modifier, 4 Wt Oz

 

[rumple]

I changed the diff oil in my 2002 LS Explorer twice. First change I used Lucas 75W-140 full synthetic with limited slip fluid all ready in the oil. I found that I had clutch chatter from the rear after the fill especially when cold.

I changed the fluid out for Amsoil 75W-140 Sever Gear *and* used 4oz of a limited slip FM that met Ford's specification (forget the brand). The rear end has been chatter free ever since, and pretty dang quiet overall.

Based on this, I would always put in the 4oz FM.

One other item - remove the bolt for the fill hole before removing the larger drain bolt. On the Explorer boards there are several cases of people removing the drain bolt first, having the oil drain and then not being able to remove the fill bolt. Truck has to be taken on a flat bed to a shop in such cases, unless you can get a mechanic to make a house call.

Rumple

 

[DieselTech]

Should be a VSS at the top of the diff. 10mm bolt holds it down. Remove it pull firmly on the VSS and with a small funnel pour in your new lube. It's MUCH easier then pumping. It's much easieer to get max fill this way also. I do suggest removing the magnet plug and filling until it runs out of the fill hole