04 grand cherokee, i am wanting to change fluids in the front & real differential, & transfer case.

any of the manuals will not say u should use friction modifiers but it is necessary if your car is getting old because if u dont wired sounds will start to come from the power train if u push your car regularly , if u dont u just need to change all the oils on time as instructed in the manual hope this helps

You only need friction modifier if you have limited slip differentials.

i use the higher weight gear oil in mine. i think its 85-140. made a world of difference.