Rear diff smell--update
A while back I had written about smelling gear lube after changing out the rear diff with Redline synthetic 80w-140. There were absolutely no leaks, nor was the diff overfilled. The odor would overwhelm the vehicle when driven, usually when I was on a slight incline and applying power to the car (99 TJ 4.0 auto). The problem turned out to be fumes coming up the breather tube mounted behind the gas fill cap. The breather tube was relocated forward next to the front diff breather, and the problem was resolved. No one I spoke to had ever seen a situation like this. I canít understand why the synthetic would give off such odor while the old fluid (85w-140 durablend) did not. Just wanted to pass this on.