Jeep Cherokee Crankshaft Rear Crankshaft Seal Leak

Had An Auto Shop Doing Some Work On Replacing Noisy Bearings Recently, One Of Which Invovled Taking Off The Transfer Case And Replacing The...

Because Of The Mileage On My 96 Xj,like A Dummy I Started Putting Full Synthetic Oil In It. I've Heard That Doing That Would Cause The Seals...