Rear Diff Fluid Change Quastion

[2000co]

I'm getting ready to change the rear diff fluid. I have 05 Mountaineer v6 AWD with AdvanceTrac.

I called 2 delaers to check if they have the xl3 friction modifier and both told me I don't need it since I don't have limited slip diff bases on my Vin number.

How can I check if I have limited slip diff? Will it hurt to add the friction modifier even if I don't have limited slip diff?

Should I buy Valvoline or Mobil1 75w-140 oil? Thanks

 

[Mikerider]

Check the vin tag on your door, if axle code 45 or 46 you have an open diff no friction modifier needed. If your door code is D3 or D4 you have a LS and need the friction modifier.

You can also check the tag on the rear diff housing. should say something like 3 73L for limited slip diffs.

 

[2000co]

Thanks!