Rear Diff Fluid Change Questions

[2000co]

I'm planning to change the rear diff fluid in my 05 Mountaineer. It's not LS diff and it's making whine noise once you hit 45 mph. I'm going to use Mobil1 75w-140 gear oil.

Is it okay to use the XL-3 friction modifier if I don't have LS? Will that help with the whine noise? Do you recommend a different friction modifier?

Should I use the black or green Permatex rtv for the drian plug or do I need to use the white thread sealant? Do I use it on both drian and fill plugs?

Do I need to add the extra pint in my rear diff?

What's the best method to open a stuck drian plug? Can I use heat?

 

[mountaineer2004]

I had the diff fluid changed by my mechanic.
He used the fill hole to both siphon out the old fluid and replace with new.
Don't know which type exactly, just remember it was the recommended one.

 

[Mbrooks420]

The limited slip additive won’t hurt anything. I’d wire brush around the plug and spray with a good penetrating oil. A little heat won’t hurt anything. If the gears are whining though, some fresh oil probably won’t stop it.

 

[TechGuru]

I'm planning to change the rear diff fluid in my 05 Mountaineer. It's not LS diff and it's making whine noise once you hit 45 mph. I'm going to use Mobil1 75w-140 gear oil.

I would use Valvoline. Comes in squeezable bags. Got it at Walmart for $12.47 each at the time. It has LSD additive in it so you won't need Motorcraft XL3 especially not even having a LSD, no it won't help the noise. The only thing that helps the noise is thicker oil. I've heard of some adding black lithium grease to thicken the oil.

What's the best method to open a stuck drian plug?

 

[TechGuru]

He used the fill hole to both siphon out the old fluid and replace with new.

I would not use this method especially if it is grinding as it won't drain the metal shavings out the bottom...

Also be sure to clean all the build up off the magnet plug with some dawn dish soap.

 

[2000co]

What you recommend using on the drain and fill plugs?

Should i use the Permatex 82180 Ultra Black, Permatex green 81182 Gear Oil, or Permatex 59235 High Temperature Thread Sealant?

Advance doesn't carry the XL-3 friction modifier, can i use a different one or only the XL-3?

 

[Mbrooks420]

I’ve never used anything but Teflon style tape on the plugs. They are tapered pipe taped holes and require zero sealant.

 

[TechGuru]

Advance doesn't carry the XL-3 friction modifier, can i use a different one or only the XL-3?

OReilly's and Ford are the only places that sell it.

But like I stated before, you don't need it without a LSD. It's to help the clutch pack slip correctly, it does nothing for the gears.

 

[Mbrooks420]

You don’t need any friction modifier.

 

[MakinJeepsWeep!]

I would simply put back in what it calls for nothing more. To drain and really get clean remove the housing cover that might help whine some. while cover is off might help you to get fill plug loose.

 

[jr230]

I'm planning to change the rear diff fluid in my 05 Mountaineer. It's not LS diff and it's making whine noise once you hit 45 mph. I'm going to use Mobil1 75w-140 gear oil.

Is it okay to use the XL-3 friction modifier if I don't have LS? Will that help with the whine noise? Do you recommend a different friction modifier?

Should I use the black or green Permatex rtv for the drian plug or do I need to use the white thread sealant? Do I use it on both drian and fill plugs?

Do I need to add the extra pint in my rear diff?

What's the best method to open a stuck drian plug? Can I use heat?

use fords recommended type of oil don't overfill look up how much and what level noise can be gear wear, bad bearings
if you have lot of metal in oil its heading to fail even could be axil wheel bearings look up scotty kilmer he has recent video how to find noise