Hey guys and gals. Purchased my 99 TJ a few months ago. It was owned by an older lady, then here grandson had it for about 12K miles. Jeep only has 90k miles on it and I am going to change all fluids listed in the title. The jeep has the trac lok differential rear axle. Do I need to add an additive for this diff? Also any recommendations on oil brands, Im in Ga so more heat than cold. Dana 30 and 35, and it is a 5 speed with the 4.0 engine.