Front/Rear Diff Oil Viscosity??

[jayhawkexplorer]

I've been searching on here and looking in my owner's manual but I cannot find a definitive answer to my question. What viscosity oil do I use in my front/rear differentials? Here's the info from the owner's manual:

'97 Explorer XLT 4WD with 3.73 open rear differential

Front Dana 35: 4x4 Gear oil, Ford part #F1TZ-19580-A, Ford spec #WSL-M2C191-A

Rear axle: Motorcraft SAE Prem Rear Axle Lube, Ford part #XY-80W90-QL, Ford spec #WSP-M2C197-A

Does that mean I use 80W90 in the rear axle? I have no clue on the front axle. Thanks...

 

[F14CRAZY]

People suggest using 75-140 synthetic, but I used 75-90 because I can't find Mobil 1 gear oil in 75-140 around these parts.

I just had my rear differential pumped out and refilled with it today at the local quick e lube.

 

[Rhett]

On my truck (94) the spec is 75-140 for both front and rear. I think the spec is about the same for all of our trucks with the 8.8. Many people run slightly different viscosities and report no trouble. I run 75-140 AMSOIL synth gear in the rear. I haven't pumped out the front yet, but I'll switch it eventually..

Don't forget to add the friction modifier to the rear if you have limited slip.

 

[jayhawkexplorer]

What about using 80W90 Amsoil in the front and rear??

 

['96explorereddiebauer]

People suggest using 75-140 synthetic, but I used 75-90 because I can't find Mobil 1 gear oil in 75-140 around these parts.

Ditto that.

But I actually took the cover off and man...it looked filthy in there. I had to pump the front one out because there's no way of taking the cover off.

 

[Bik'nSport]

If the owners manual calls for 80w90, can you use a 75w90 synthetic like Mobil1 or is it not heavy enough? I have not been able to find a full synthetic 80w90 around here.

 

[jayhawkexplorer]

Amsoil makes one.

 

[F14CRAZY]

[QUOTE='96explorereddiebauer]Ditto that.

But I actually took the cover off and man...it looked filthy in there. I had to pump the front one out because there's no way of taking the cover off.[/QUOTE]

Yay! Someone else agrees with me. I do know it's best to take the cover off to get out more crap and replace the gasket if it's leaking. So I had my local quick lube do only a half @$s job, but they basically did get it all out considering the amount the dude dumped back in. It was pretty discolored but I didn't see any grit when he "handed" me a sample.

It's not perfect doing this way, but a ton better than NOT doing it at all. Remember, "better out than in" -Shrek

 

[Jeff]

I just got off the phone with Redline and for my 97 Control Trac, conventional rear, they are recommending 75-90. 3.5 pts in the front and 5.5 in the rear. Doing the math that means 5 qts with a half quart left over for spilling and playing with the wonderful red elixer.