I have a 2001 4x4 and just noticed that when in 4H the front end is grabby when I turn very sharp. It feels like the differential is not allowing the inside tire to slip. I have not changed the Lube in it yet and have 61,000 miles on the truck. My thoughts were to try changing the gear oil but thought I would seek opinions. Is there a need for the friction modifier in the front end? I would also appreciate info on what oil to use.

 

Use 75W 140 synthetic lubricant, Driving in the 4H and 4L positions on
dry hard surfaced roads may cause increased tire wear
and damage to the driveline components.
Does truck turn normally when out of four wheel drive?

 

With open knuckle U-Joint front ends that grabby wheel shake is normal when In 4WD, especially when trying tight turns, it has nothing to do with the "open" diff but the fact that the U-joint is being forced to change direction while being powered. no friction modifiers need in the front diff, You should replace the diff oil anyway but it will NOT fix your front end. dont over fill the diff, check specs I think it calls for 1/2inch below fill hole. also clean vent hose and vent to ensure you dont develop any front axel or pinion seal leaks

 

Truck works fine in 2WD. I don't remember ever having this problem before but maybe it has been there. 4H and 4L work fine but the front end feels like the Diff is not working correctly....similar to haveing the truck in 4L and the rear end Diff lock engauged.

 

I don't know about everyone elses experiences, but every 4wd truck I have ever owned did, and my 99' does it, if you are on asphalt or real hard pack, AVOID it, it is real hard on the u-joints.