Most of the synthetic oils have friction modifier in it already. Some people claim it’s “not enough and you should add a bottle” but the more friction modifier you add, the less the clutches grab.
I've noticed the same thing Lil_Blue_Ford has about synthetic gear oil. A lot of times, it will say somewhere on the bottle there is additive already in there.
Unfortunately it wasn't synthetic. Had a 4 hour run to the nearest town and used what I could. Never had manual to tell me proper oil, otherwise would have got someone to pick me up some. Probably put on 10k since.
Some non-synthetics have it too. All the friction modifier does is keep the clutches from grabbing hard so it makes it smoother and quieter. Personally, I’d rather it grab a little harder.
So many jokes here...
UPDATE. Now that the snow is gone and I'm driving in 2wd there's no clunking whatsoever. I did buy a cv kit from Amazon for the front driveshaft early fall and installed it. So either being cheap Chinese metal and something is broken. ( checked all bolts were tight
) or something wrong with transfer case. I'm taking it in to a shop next week. It's not constant in 4wd. Just sporadic. But like I said last 3 days never happened once. And up to 60mph
