If you do not feel a chatter (or shimmy) when cornering with the diff warm (which is about an hour drive time or so), don't do a thing.

If you put too much, your LSD won't work at all.

 

exactly but usually a dealer will put it in so they don't have a call back the downside is it can make you LS worthless or more worthless if you will

but I am not saying your 2012 D80 would require it just the normal procedure for differentials that can require it like mine

it should be in your manual just like the fact the Dana 80 was the DRW rear axle on a F250-350 Drw

 

Just curious, on my 14 F350 the duffs are supposed to use the friction modifier; I just had my stock diff cover swapped with my ATS cover and other than the fluid being dark grey and having some bits of metal in it, my mechanic said the local dealer didn't have the friction modifier, but said it was alright to drive without it. I'm wondering is this true or false?

 

it's fine like mentioned usually you add the modifier to let the clutches slip more and reduce chatter when turning from the clutches not slipping smoothly