Just changed the rear diff oil on my 96 and had a question on the friction modifier. It is just the regualr stock rearend (not LS-jacked it up and put it in neutral and 1 tire spun 1 way and the other the other way). Added the 80/90 as recommended by the owners manual. Does it still need the friction modifier? I am sure it will not hurt if I do add it, better to be safe than sorry. Any thoughts?