If you use normal gear oil you will soon burn it out, special LSD oil is needed, Halfords sell castrol stuff which is ok to use but the best is the proper spec Ford stuff which they still sell, plus add some 'ingredient x' as it's known (Ford sell this also) which is an additive that helps stop the plates in the LSD binding. Both these are available in a kit from the Capri club (Part No Z002) and costs £28.

Steve