Do I require Ford's XL-3 Friction Modifier?

[Kira]

I've just been phoned by my pal's son who cured a severe differential chatter in his '05 Explorer by replacing his fluid with some treated with Ford's XL-3 FM. He had used another kind earlier.

I have the same rear in my '05 Ranger (8.8" limited slip, 4.10) and want to change my fluid.
I bought RedLine brand FM thinking RedLine was king on all fronts.

I did a search here and read many posts from members who just included it on their "supplies bought/used" list. Nobody mentioned having had chattering etc.

What should I do for my middle aged girl?

 

[WylieCoyote]

I put Redline in my Mustang. A fine gear oil, but doesn't have enough friction modifier in it for the Mustang LSD. It moaned during any low speed turns. A bottle of XL-3 cured it.

 

[tasch72]

XL-3 is pretty affordable, even at a dealership, and does the job right the first time.

 

[bdcardinal]

Is your Ranger a FX4 Level 2 by chance? If so it has a Torsen which does not use FM. If it isn't that specific package, then it has a trac-lok and it does need FM.

 

[ripcord]

I've had good luck with Lubegard limited slip additive and it's always available at my FLAPS.

 

[Kira]

Is your Ranger a FX4 Level 2

No. It's an FX4 Off-Road.

 

[blupupher]

Most rear diff fluids don't have enough FM for Fords.
The XL-3 is good stuff, but be aware, it stinks something horrible. Like gear lube x 10.
And don't get any on you or any clothing, and if you get it on rags, just toss them. If you try to wash them, they will just stink up whatever you wash it with.

 

[cmarshall78]

I just changed the rear diff oil on my F150 a few weeks ago and put in valvoline 75w140 with friction modifier already in it. Anticipated having to add more but ended not needing to.