Differential fluid Question????

[oceantech84]

I've searched around forum,reddit and Google but I would love to hear some opinions on here for a 23' 501a

I have in my garage a 5 gallon bucket of Royal Purple 80w90 max gear. I know the book calls for 75w85 but would like some opinions if I should go for the swap or stick with the book. I also had a hard time finding if I need friction modifier or not.

Thank yall for any help.

 

[Badgertits]

I think I put Amsoil 75w90 in mine, works fine, the front diff I went w/ factory fluid it’s also very hard to swap so had dealer do, you’d be fine w/ that gear oil

 

[SurfRaptor]

Motorcraft® SAE 75W-85 Premium Synthetic Hypoid Gear Lubricant / XY 75 W85-0L (WSS-M2C942 A)

Ford seems to be the only one that is making 75w-85. Everyone else in the aftermarket is 75w-90. I doubt there would be an issue but I always match the specs on fluids so I have proof to retain my warranty. I'm not saying I only buy motorcraft but I would try and get something that has WSS-M2C942 A if that's even a possibly.

 

[Badgertits]

Motorcraft® SAE 75W-85 Premium Synthetic Hypoid Gear Lubricant / XY 75 W85-0L (WSS-M2C942 A)

Ford seems to be the only one that is making 75w-85. Everyone else in the aftermarket is 75w-90. I doubt there would be an issue but I always match the specs on fluids so I have proof to retain my warranty. I'm not saying I only buy motorcraft but I would try and get something that has WSS-M2C942 A if that's even a possibly.

The Amsoil 75/w90 shows as a manufacturer accepted substitute for mercon 75/85

 

[SurfRaptor]

The Amsoil 75/w90 shows as a manufacturer accepted substitute for mercon 75/85

Good to know. I’m doing my diffs soon myself.