Is there a difference in 2 cycle oils? I was at WalMart today and in the boat section there was labeled  2 cycle "outboard" oil. Then in the Automotive section there was plain 2 cycle oil. Is there a difference between Outboard 2 cycle oil found in the boating section and regular 2 cycle oil found in the automotive section?

I Guess what im asking is,can "plain" 2 cycle oil be used in an outboard in instead of  2 cycle oil thats labeled specifically for outboard or marine applications. What ,if any,harm will occur?

Short answer, any oil that meets TC-W3 specs can be run in any water cooled two cycle motor.  Notice I said water cooled, don't use TC-W oils (the W is for Water) in air cooled two strokes.

Now, are all TC-W3 oils made the same, "NO".  Would I use just any TC-W3 oil in my outboard "NO"

Cheap oils are cheap for a reason, they don't have all the wear preventing and carbon/gum reducing additives the better oils have.   Pensoil might make oils for 20 different brand names, but that doesn't mean the same thing goes into each brand.

You also have three basic types, Fosil based, 100% synthetic, and blends of fosil based and synthetic.  Fosil based being the cheaper, 100% synthetic the most expensive and the blends somewhere in between.  Even among the three basic types there are big differences in additives that diffent brand names use.  

Now you will hear all kinds of testamonies as to which is best, but I don't buy anything cheaper than Pensoil.  I run 100% synthetic in everything I have but my Rude and run the factory recommended Evinrude oil in it.

If the oil is not TCW-3 do not use it in your outboard. Do not use oil for air cooled engines in your outboard.

If it doesn 't say OUTBOARD oil don 't use it.

I'd go a step further and say.... If it's not reccomended by your Outboard Manufaturer Don't Use It!!!!