Do not use petroleum based lubricants and oils on any firearm that will be fed BP loads. The fouling will become really bad and cause probems if you use petroleum based oils and lubricants.
Use a BP lube like Borebutter (TM) for lubricating bullets and use Ballistol (TM) for cleaning and oiling the firearm.
http://cap-n-ball.com/ballistol/
http://www.logcabinshop.com/catalog/borebutter.html
Personally I recommend that you get an inexpensive Hawkins rifle from CVA for learning about BP. Then move up to a BP cartridge rifle.
http://www.cva.com/
http://www.cva.com/products/rifles/hawk.htm