How long does it take to replace both of them?

 

The dealer will charge ~$2700 each just for the part. If you need new turbos, consider rebuilding them or upgrading. Rebuilding will save you $$ and can be done tighter than stock. Search here and send a note to Kevin....who can help you if your turbos are dying.

Did you find where the leak was coming from? As you know, there are many places where an oil cooled engine can leak.....