Chainsaw Repair

   Chances are there would never be a problem without the o ring, But never trust a little bit of grease to make a seal.       
  Polaris uses a similar setup in the chain case on their snowmobiles, o ring on the shaft.  One day it was leaking on me after a rebuild, I pinched the o ring, and simple gravity let oil leak out, no pressure or vacuum involved here either.
  Even a dried out o ring will still make a seal when wedged in there, it just comes out in pieces like mine did on the 372 that Tim has right now for his tutorial on crank bearing changes.
  Id like the o ring in my bottom end, just tell me what the o ring costs, I don't cut corners on many things!!  The possibility of sucking air into a bottom end doesn't sound like its worth the chance to omit the o ring.