I also checked on the internet and found that they have a new F series out board motors that use a mixture of 1:100. They also come with a 5 coat salt water protection inside the motor and used less fuel than other outboards.
I was thinking about buying a 9.9 hp Yamaha, but the dealer told me that I could get the 15 hp Yamaha for the same price and both models weighed the same. It just so happens that my 12 ft. boat has a max hp capacity of 15 hp, so I bought it. I am still breaking in the new motor, 10 hours with a 1:25 mixture, after that it uses 1:100 mixture. But in the instructions, it called for after 2 hours of use to accelerate it full blast for 10 minutes. The power surprised me, my boat was flying at high speeds, skipping over the water. I also notice that this motor comsumes very little fuel, has some kind of double recyle fuel burning system, it only used about 3/4's of a gallon of fuel after 3 hours of running the motor, my old Johnson 6.5 would have used about a gallon and a half of fuel.
I really like it.
Eddie