My best friend ran low on oil and something in the head is now making a banging noise. I shut it down immediately. Anyone know by this very brief description what I might of messed up. It still runs,but its hard to get the motor to turn. I'm pretty good with a wrench , is this something I can tackle? How about a worst case and least case scenario.

 

Well you could have spun a bearing in your crank, or a ring in your piston could be messed up. Probably well have to take it apart to check out.