I don't claim to know the direct answer to your question, but I can tell you
that I have been using 50:1 on ALL my two stroke engines ever since the oils
designed specifically for that mixture became available. Some of those
engines called for 25:1, but seem to run just fine on the 50:1, and for
quite a few years now. I would not use 50:1 unless the oil is specifically
designed for it.

BS

"J. K. Smith" wrote in message
...
I would like opinions from you boat wizards familiar with Zen and
outboards.

My Nissan 3.5 drives my small Portaboat around nicely but its user manual
and the label on the fuel tank disagree. The manual tells me to use 25:1
fuelil ratio and the label says 50:1. I've been running 25:1 because
it's what I saw first. I don't notice significant smoke and haven't had it
long enough to foul the plug yet.

Any ideas on which way is best or whether this is even a subject worth
discussing? Thanks.