"If it ain't broke don't fix it"

 

x2

 

You must be proud of how much of a douche you are...

To the OP putting oil back in won't fix your leak. Your rear main was already bad, oil sludge plugged the leak and the synthetic oil did it's job and broke down the sludge.

Replace the rear main seal or start putting dino oil in untill you've got a 100k miles worth of sludge.

Probably easier and cheaper to replace the seal.

This is why it's best to stay with oil if that's what has been used in it for years. New engines go with synthetic if you want to, but never in an old engine if you don't want to replace seals.