F-1Fizzy

ok well im approaching the 80k mark with my truck and i am going to be changing the rear end fluid soon...i am going to be using Royal Purple gear fluid for sure but i just dont know which one i need to use?? i see there is 75w90,75w140,85w140,etc... so which one would be best to use? im a new york city driver....and this is a 5.4L with an LS rear...also any other tips,or tricks with doing this id appreciate....first time changing the fluid on my truck....

GATORB8

Ford Specification WSP-M2C197AC197A
REAR AXLE
Rear axle Motorcraft SAE 75W-140 High Performance Rear Axle Lubricant (synthetic)
Ford Part Number XY-75W140QL
Ford Specification WSL-M2C192A2C192A
NOTE: Use Additive Friction Modifier XL-3 or equivalent for complete refill of Traction-Lok axles.

NOTE: Vehicles with 8.8/9.75 inch axle and 10.25 inch rear axles are filled with a synthetic rear axle lubricant and is considered lubricated for life. These lubricants do not need to be checked or changed unless a leak is suspected, service is required or the axle assembly has been submerged in water. The axle lubricant should be changed any time the rear axle has been submerged in water.

NOTE: For 10.25 inch Traction-Lok axles, use 6.5 pints (3.1L) of Motorcraft SAE 75W-140 Synthetic Rear Axle Lubricant and 8 oz. (236 ml) of Additive Friction Modifier XL3 or equivalent meeting Ford Specification EST-M2C118-A.

ford4wd08

so let me get this right the lube is for life? i dont know if i could trust that...

Mod (Ret.)

Yea, they all say that now....my wifes BMW has "lifetime" transmission fluid too. I don't buy that one either!

F-1Fizzy

yea idk about lifetime...its hard for me to even buy 100,000 miles let alone a lifetime which will be much more...i take it they expect everyone to get rid of cars after 40k and move on