Why would it slip and cause issues... If you used something that didn't contain additives or chose not to use the additives separately all it would do is cause the diffs to lock up more easily, not slip. The additive actually causes slippage so you don't lock up going around corners and such causing tire chirp. A lot of guys actually choose not to use the additives or use only half of the recommended amount for added performance off-road.
2008 GC CRD, OME 2" lift kit, 265/70/R17 Cooper Discoverer S/T's, 1.5" Spidertrax spacers, gutted turbo resonator