I have used the MMO/2 cycle mix in the past but for the last 100
    hours I
have been using the Wal-Mart Marine 2 cycle oil.  After reading up on
the different classifications of 2 cycle oil (most brands are all in
one now) and looking at the temperature profiles for the apex seals I
concluded that almost anything would do a better job than crankcase
oil of lubricating the seals.  And 2 cycle certainly leaves less
residue than crankcase oil.  Mornin' Ed,
 
Is MMO and 2-cycle oil close to the same thing?  When I try to
rationalize using one over the other, I come up with one other issue. Our pre-mix oil does get scavenged into the crankcase to some extent. MMO is made to be used in fuel, and oil, so that's not a problem.  I
can't say that I've ever heard anyone comment on the effect that
2-cycle oil has in our crankcase. I've wondered if this alone is a
reason to prefer MMO over 2-cycle oil.   Another question just came to me.  Does oil injection cause oil to be
scavenged into the crankcase?  I'm assuming it would be less than what
we get with pre-mix, though some must make the trek.  I wonder if
Mazda considered that when deciding to use crankcase oil for the apex
seals?  Of course originally, they weren't using the dripper
injectors, but rather injecting the oil into the fuel/air stream at
the carb.  Cheers,
Rusty