2003 Explorer XLT V6 Rear End

[03Explo20]

Searched a bit on here as the rear end in my Explo started the whining yesterday on the way home from work (78k miles). It only did it a few seconds then stopped. It sounded like a siren wailing up.

My axle code is a 45 which states it's an open axle. I have the towing package on the truck and was assuming it would be a LS differential????

Anyway, I'm planning on changing out the gear oil. I was going to purchase Lucas 75 w 140 Synthetic to put in and was wondering if I should use that or go with something different now that I see it's an open axle. Also, what about the friction modifier, would that be required for this open type axle?

How long can this go with the whining before a major issue occurs?

 

[TechGuru]

My axle code is a 45 which states it's an open axle. I have the towing package on the truck and was assuming it would be a LS differential????

LS has nothing to do with towing, it's the ratio that matters. 45 is 3.55 which is not very good for towing, you really want the 3.73 for towing.

Anyway, I'm planning on changing out the gear oil. I was going to purchase Lucas 75 w 140 Synthetic to put in and was wondering if I should use that or go with something different now that I see it's an open axle. Also, what about the friction modifier, would that be required for this open type axle?

Any are fine really. I'd go with Valvoline or Lucas.

How long can this go with the whining before a major issue occurs?

Indefinitely, kinda. Eventually over years it will become so loose inside that something will break. You'll want to replace it before then. Rebuilds cost around $800. I'd just pop in a assembly from a salvage yard which can usually be had for under $300.

BTW, if rebuilding and planning to do a lot of towing I'd put a 4.10 in it.

 

[03Explo20]

Hey TechGuru, should I also add the friction modifier in with the gear oil on the transaxle?

 

[TechGuru]

Hey TechGuru, should I also add the friction modifier in with the gear oil on the transaxle?

No. Don't need it for non LSD.

 

[Drewmcg]

Wish I'd read this before dropping $40 (talked 'em into a $5/quart discount) at my local Ford dealer for 2 quarts of their full synth rear diff oil that I put in yesterday. Oh, well, I'm a sucker for Motorcraft fluids (except engine oil), and won't do it again for another 133k miles . . . .