"Since Rollie and I have varyi
"Since Rollie and I have varying opinions
Like he says however, depends on the application.
On the back of a 12 or 14 foot aluminum, the 75 pound 9.9 2 stroke will ultimately burn less gas than the 120 pound 4 stroke simply due to the 45 extra pounds (all else being equal).
Any difference you will notice? not likely (in the above application).
On a 100 hours of operation (recommended service interval) and say 40 gallons of gas burned -
2 stroke would require 1 gallon of 2 stroke oil (15-25 bucks depending on brand)
4 stroke would require 1 quart of 10W30 (2-5 bucks for "dino" oil, about double that for sythetic) and an oil filter ($13.75 from Yami)
In this horsepower, there is no significant advantage to either motor in terms of performance at top end - so it comes down to initial cost and on-going costs.
The on-going will be quite similar on a little motor. Yes, you have to buy 2 stroke oil, but you still have to do an oil/filter change on the 4 stroke (more economical the larger the engine). Plus there are far more moving parts on a 4 stroke than a 2, so more (potential) for things to go wrong....."