Rear FX4 Differential Fluid

[Hardening2753]

Kind of like what I did with my previous Honda's transmission fluid, I plan to run nothing but the OEM fluids through the PTU and RDU, and also using new caps or whatever they're called instead of RTV. I run my vehicle decently hard and may as well spend a few more bucks. I'll still be saving thousands doing my own maintenance over the life of the vehicle anyway.

Agree on money savings but you always catch any issues quicker and could save money that way too.

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[dalola]

Did my (2nd) oil change yesterday, along with the PTU & RD, at 13k miles. Like most have been finding, both were pretty gunky. I got just under 1 pint out of the PTU, and just over 1 pint out of the RD. Due to the low volume of oil in these, I'm thinking I may adopt 20k change intervals moving forward. Maybe overkill, but it's easy enough to do, and you can get two changes out of a quart for each, so pretty cost efficient.

Anyway, just an FYI for those still considering an early first D&R, seems worth doing based on reports so far of most of us finding gunky oil. If the oil looks better on the second change, then I would consider stretching out to 30 or 40K. But glad I did it early for the first one!

 

[Montana]

Did my (2nd) oil change yesterday, along with the PTU & RD, at 13k miles. Like most have been finding, both were pretty gunky. I got just under 1 pint out of the PTU, and just over 1 pint out of the RD. Due to the low volume of oil in these, I'm thinking I may adopt 20k change intervals moving forward. Maybe overkill, but it's easy enough to do, and you can get two changes out of a quart for each, so pretty cost efficient.

Anyway, just an FYI for those still considering an early first D&R, seems worth doing based on reports so far of most of us finding gunky oil. If the oil looks better on the second change, then I would consider stretching out to 30 or 40K. But glad I did it early for the first one!

Same. 20k sounds about right for me too the. I'll go from there. 30k will be my max though. $60 every 20-30k is cheap and worth it.

That fluid was awful though. Bleh. Like snot built up on the plug and everything lol.

First time is always special

 

[Decayed]

I'm going to do the initial fluid change at 10k to check the condition. I've been doing a lot of towing. Then at the regular 30k intervals.

This is reasonable. Even without towing a lot, they recommend changing the ATF at 30k under severe driving conditions which includes frequent stop and go driving. That's all I do, so 30k it is.

Let us know what the fluids look like and if you find metal bits.

 

[Montana]

Well, I forgot to look on the wrappers for the part number or get it from the dealer when I picked it up, but does anyone know the part number for the drain plugs?

I ran a search and found 6C2Z-4N282-AA

Can someone help confirm that is the correct plug? I'd like to have an extra just in case my theory of not needing to re-use them is wrong and just because I stash parts in my garage

Looks like that's a pretty universal plug they use on a lot of models too.

And the PTU is GN1Z4N282A for the drain plug.

 

[bgn]

Well, I forgot to look on the wrappers for the part number or get it from the dealer when I picked it up, but does anyone know the part number for the drain plugs?

I ran a search and found 6C2Z-4N282-AA

Can someone help confirm that is the correct plug? I'd like to have an extra just in case my theory of not needing to re-use them is wrong and just because I stash parts in my garage

Looks like that's a pretty universal plug they use on a lot of models too.

And the PTU is GN1Z4N282A for the drain plug.

Can someone confirm these? I have fluids on the way from RockAuto.

 

[Montana]

Can someone confirm these? I have fluids on the way from RockAuto.

Yes, those are correct. You can do what I did and get the new set, then apply thread locker to the old set for next time, so it's dry when you use them.

Check here for any other part numbers. I'll add those to the list too.

Do you have a pump for the fluids? If not, here is what I use.

 

[bgn]

Yes, those are correct. You can do what I did and get the new set, then apply thread locker to the old set for next time, so it's dry when you use them.

Check here for any other part numbers. I'll add those to the list too.

Do you have a pump for the fluids? If not, here is what I use.

Thank you. I picked up the same pump yesterday because it was the cheapest I could find. Good to know it fits the bottles.

 

[DoubleR]

Can I get by with using Mobil1 75W90 gear oil???

 

[billbillw]

Can I get by with using Mobil1 75W90 gear oil???

No. It must have the special additives (friction modifiers) for the clutch packs. Regular gear oil is only good for non-limited slip differentials.

 

[DoubleR]

No. It must have the special additives (friction modifiers) for the clutch packs. Regular gear oil is only good for non-limited slip differentials.

Mobil 1 gear oils have a Limited Slip additive... The LS on the bottle.
Mobil 1 Synthetic Gear Lube LS 75W-90 contains special friction modifiers designed for limited slip-type differentials. In most applications, the addition of special LS (limited slip) additives is not required.

 

[Decayed]

Mobil 1 gear oils have a Limited Slip additive... The LS on the bottle.
Mobil 1 Synthetic Gear Lube LS 75W-90 contains special friction modifiers designed for limited slip-type differentials. In most applications, the addition of special LS (limited slip) additives is not required.

They set the spec for a reason. You might be better off not changing it at all instead of using the wrong oil.

 

[DoubleR]

Did my (2nd) oil change yesterday, along with the PTU & RD, at 13k miles. Like most have been finding, both were pretty gunky. I got just under 1 pint out of the PTU, and just over 1 pint out of the RD. Due to the low volume of oil in these, I'm thinking I may adopt 20k change intervals moving forward. Maybe overkill, but it's easy enough to do, and you can get two changes out of a quart for each, so pretty cost efficient.

Anyway, just an FYI for those still considering an early first D&R, seems worth doing based on reports so far of most of us finding gunky oil. If the oil looks better on the second change, then I would consider stretching out to 30 or 40K. But glad I did it early for the first one!

What fluids did you use for the PTU and RD? Did you use Motorcraft?

 

[dalola]

What fluids did you use for the PTU and RD? Did you use Motorcraft?

Yes, OEM spec Motorcraft purchased from Rock Auto. For whatever reason, Ford dealer pricing on these fluids is ridiculous.

 

[DoubleR]

No. It must have the special additives (friction modifiers) for the clutch packs. Regular gear oil is only good for non-limited slip differentials.

The Motorcraft 75W85 gear oil does not have friction modifiers in it... (see pic of label)

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