Hello, I recently inherited a pristine 59 ford fairlane. It was sitting for many years and I have changed all the fluids among other work to get it roadworthy again. I had several quarts of mobil one synthetic gear oil, so that is what I used in the manual transmission. The rear seal leaked profusely (even before the change) so I replaced the rear seal. The new seal continues to leak a lot. I was careful not to damage it during installation. Could this be caused by the use of synthetic gear oil? If so, will a change to conventional gear oil stop the leak or do I have to change the seal again? Lastly, the yoke coming out of the transmission has some small pits. There were no rough edges, though I did polish it up a bit with some wet/dry sandpaper. Do you think these minor pits might contribute to the seal leaking? Thank you all very much for your responses.