Transfer Case and Front/Rear Axle Fluids

[Justinwht]

Does the front axle gear need friction modifier as the real axle does?

Quoting from the owner's manual (tips hat to www.JustGiveMeTheDamnManual.com), it has two footnotes.
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Transmission fluid -
Motorcraft MERCON ATF - 5-speed manual (Yes I know to use Mercon and *not* Mercon V)
Transfer case -
Motorcraft MERCON ATF - 4WD
Front axle lubricant -
Motorcraft SAE, 80W-90 Premium Rear Axle Lubricant
Rear axle lubricant -
Motorcraft SAE, 80W-90 Premium Rear Axle Lubricant (Refer to - Footnote 6)
Motorcraft SAE, 75W-140 High Performance Synthetic Rear Axle Lubricant (Refer to - Footnote 7)

Footnote 6 - Vehicles equipped with 4.0L OHV V6 and4.0L SOHC V6 engines may be equipped with a conventional rear axle. Refer to your scheduled maintenance guide for axle fluid change intervals.

Footnote 7 - Vehicles equipped with 4.0L OHV V6 and4.0L SOHC V6 engines and 3.73:1 or 4.10:1 rear axle ratios or with a 5.0L V8 engine require synthetic rear axle lubricant. Rear axles containing synthetic lubricant are lubricated for life. These lubricants are not to be checked or changed unless a leak is suspected or service is required. The axle lubricant should be changed any time the axle has been submerged in water.

Add 118 ml (4 oz.) of Additive Friction Modifier C8AZ-19B546-A or equivalent meeting Ford specification EST-M2C118–A for complete refill of Traction-Lok axles.
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I was thinking of using Royal Purple for rear differential. What should I use for front end? Does it need a friction additive?

 

[RangerX]

Front axle doesn't need it. It's only to help a limited slip diff, which the front does not have.
Rear axle only needs it if it has a limited slip.

 

[Justinwht]

It dawned on me last night that of course the front end wheels are locked to begin with and there isn't any differential rotation.

While the rear end is Traction Lock or Ford's name for limited slip, I'll check the metal tag on the rear bell housing to confirm rear end type. With model changes you can't be sure what you have.

 

[Justinwht]

I looked at the build sheet via the VIN and it didn't say limited slip. Could it mean you can should assume it is limited slip and simply not listed or is it really a standard differential?

/Added
Am thinking all Rangers and Explorers had limited slip. But with Ford's design changes... who knows.

 

[drdoom]

Look on the door jamb sticker if possible, it should have axle codes.

 

[drdoom]

And check your vent hoses while you are under there.

 

[Justinwht]

Sticker

 

[RangerX]

45 is open diff, 3.55, no friction modifier needed.

 

[Justinwht]

The owner manual refers to the 3.73:1 or 4.10:1 rear axle ratios needing the friction additive.
So with a 3.55 all I need is straight Motorcraft SAE, 75W-140 High Performance Synthetic Rear Axle Lubricant.

Thank you very much..

 

[Justinwht]

This helps
http://www.explorerforum.com/ntrprize/Axle.htm

 

[RangerX]

Use the synthetic if you want, but you don't need to. 80W90 is fine.