Maintaining Modern Outboards.Fuels
A great deal of ink has gone into articles
about outboard gasoline, what to do with it,
and what to put (or not put) into it. Among
the claims repeated in the boating press are
the following. The only problem is that none
of the authors of these articles provides a
shred of evidence that any of these measures
is necessary or even helpful.
Drain and discard all your gas at the
end of the season because it would
ruin your motor if you were to use it
the next season.
Fill up your tanks and add gas stabilizer;
otherwise the old gas will gum
up your carburetors.
Fill up with high octane gas at the
end of the season and add an octane
booster at the start of the next because
gas looses its octane in storage
and will ruin your engine.
Add two-cycle oil and methyl hydrate
to your gas before storing it (for
both two- and four-cycle engines) to
absorb moisture and prevent condensation
in the engine.
Use any of the many mechanicin-
a-bottle fuel additives to clean,
repair and generally reinvigorate
your engine.
I've run outboards many years on the
previous season's leftover gas and never
had any of the dire consequences these
authors assure us will result from stale
gas. Maybe the new electronic fuel injection
engines are more sensitive to gas quality, but
I haven't seen the evidence yet. The only
thing on the subject that can be said with
any certainty is that a fuel tank left empty
in a cold, damp climate will generate some
condensation and the resulting water will
have to be filtered out before it reaches the
induction/injection system.
If you believe in fuel stabilizers/additives,
by all means use them. If you have
field experience that supports the claims of
these authorities, get in touch with me and
let me know what you have learned. I'll pass
it on to others. Otherwise, just use good filters
and don't worry about it.
blasphemy!!
. My mechanic, at the time told me these were notorious for gumming up. (The motor was a 2 stroke oil pumped 90hp Mercury.) He recommended stabilizer and said after 30 days the fuel without stabilizer would begin to break down. As the old adage goes, the best day for a boat owner is the day he buys his boat and the day he sells it. This was certainly true for me with this particular money pit 
!
. If the gas sits more that 5 to 6 weeks I siphon it for my lawn tractor and try to keep the gas in the tanks relatively fresh. I was surprised at how fuel efficient the Yamaha 50 is and have siphoned several times because of underestimating how much gas I'll use when we're underway. I guess too much is always the better way to go 
