ScaldedApe

So I'm trying to order differential fluid for both the front and rear diff and I'm getting two different numbers. My owner's manual says to use 80w-90 front and rear and motorcraft.com says to use the following:

"Part Description: (Motor Oils And Lubricants Usa Usage); Hypoid gear lubricant - ""Use 75W140 synthetic oil ONLY'' "

I know this subject gets beat to death, but I wonder why the difference in weights? Did Ford come to some new understanding?

Just call me Sean

iTrader: (1)

They didn't use synthetics when our trucks were new.

ScaldedApe

So does Ford now recommend this new weight and synthetic? Front and rear?

sylver91

As far as I knew only Lightning trucks recommended 75W-140 GL5. Everything else is 80w-90 with or without 4 oz of trac modifier If you have an LS.

ScaldedApe

I looked at the motorcraft part number notes and it looks like at one point it had been replaced by 75w-90. But all the numbers are discontinued.

I may just stick with synth 75w-90 since it's closet to the manual.

qdeezie

I use 75w-90 with no issues.

Flareside302

lightning's were 75w140 all others were 80w90. but 75w90 is a great alternative.