after 252,000 miles, I finally tried a motor oil other than my trusty dino grade Castrol. At a Volvo parts manager's recommendation, I tried Pennsoil (also straight dino oil) for kicks, and lo and behold 500 miles later, my rear main seal opens up! I know I'm not talking fancy oils here and don't want to hear from every Amsoil dealer that I should be using Synthetic anyway, but I am wondering 2 things:
1. could there be a correlation between swapping oils and the seal going bad? or is it simply coincidence and long overdue anyway?
2. How long do the leaks typically last before going catastrophic? I'd like to drive it about 2 hrs to a trusted dealer for the operation which will include the first clutch in this car's life.

thanks for any input,
claude
'94 855M 252,000 miles (orig. owner)
original clutch, exhaust, alt. etc.