Rear main seals are netorious for leaking on Holden motors. If it is leaking it will be a RWC isue foe you. There are products you can buy to add to the engins oil that soften the seals so they seal better , they may help . We bought one called Liquid Intelligence for son inlaws Commodores , seams to have fixed it . It is expensive though . There is enough in the can to do 2 to 3 motord depending on the capasity , so I am going to try it in my 80" engine , gear box & transfer case.

