Center diff and diff lubes

[tom255]

O my bad so lighter oil in back gives me less oversteer and heiver oil means more understeer

Not exactly ONPOWER and OFFPOWER factor here also
With hevier oil back Onpower it oversteer (your buggy tends to loose your back starts to slide) Offpower it understeer (you feel that your buggy not steer well like it supposed to)
Some basics you will find here also http://users.pandora.be/elvo/ its for onroad car but basics are same