Friction modifier or no?

[DRam2019]

I tried using the search feature but was left unsure. Getting ready to change diff fluids.
2019 2500 6.4 gasser 4x4 with anti spin. Planning on using the amsoil 75w-90 front, and still on fence of the 90 or 110 in rear.
I know the amsoil has modifiers already, but…. Should I add the amsoil slip lock as well?
Tow about 3800-9000 lbs every other weekend into the rolling hills of VT year round.

 

[kdoublep]

I'm about to do the same and it seems we may still need to add some modifier according to a few posts. I purchased the mopar modifier and the amsoil severe gear.

I would say add a bit. Or you can see if you have any chatter first then add some but you'll have to drain a bit out if you go that route.

I'm going to add a bit. YOLO

 

[Wild one]

I tried using the search feature but was left unsure. Getting ready to change diff fluids.
2019 2500 6.4 gasser 4x4 with anti spin. Planning on using the amsoil 75w-90 front, and still on fence of the 90 or 110 in rear.
I know the amsoil has modifiers already, but…. Should I add the amsoil slip lock as well?
Tow about 3800-9000 lbs every other weekend into the rolling hills of VT year round.

If you're towing that heavy through rolling hills,i'd seriously consider 75W-140 in the rear diff.It acts the same as 90 or 110 until the diff gets hot,then it provides a little more protection

 

[kdoublep]

I got 140 and I don't tow. Just haul. I would do 140 as advised by Wild one.

 

[Fatbob Frank]

Better to have it and not need it than the reverse...
All you're wasting is a couple extra bucks and it's not going to hurt anything...
But Amsoil does claim it's not needed...