<VV> Gear oil

[Joe Lewis]

Ran into a little problem after we dropped the cars engine to replace the flywheel and clutch. I have a 65 Corsa convertible with the 140 hp engine and 4 speed. At the time of doing the flywheel I decided to add the clarks finned axle cover and replace the side cover and front cover and gasket on the differential. Everything went back together fine and  a leak in the front cover was stopped by the gasket replacement. Now for what I may have done wrong. Royal purple max gear oil (synthetic) was on sale so I went overboard and purchased it. Still expensive at about $18 quart. Weight was SAE 75W-140. We filled to proper level, cold. Everything ran fine but after a long run with the car, bring it up to temperature, when I cam home I had gear oil all over the place. I check the dip stick and it was over the full level so it’s almost like the oil expanded. I opened the side cover fill hole and let it drain out (did this when engine was cold). The dip stick shows a little below full but running the car yesterday I still came back with oil all over the bottom of the car. My question is if I used the wrong oil and if I drain the synthetic out can I replace with correct oil without flushing the whole differential? As there was oil all over the place I could not find one spot is was leaking from.

Joe