Chainsaw Repair

Everything was tight when I took it all apart.  No obvious signs of leaks (dirt streaks where air was getting in or out), so I'm not sure.  What kind of oil should I be using in the mix.  I generally use the stuff I get at my local home center.  It's 2 cycle oil for small engine mixes.  Is there something better?  I just figured oil is oil.  Even if I have to spend $120 on a piston/cylinder kit it will still be cheaper than a new saw.  And this has only cost me about $50 a year to own and that includes chain, gas and oil.