I'm guessing if fuel efficiency is a concern then operation cost would be as well. If that's the case then I would suggest giving a 4-stroke some thaught.
On average 4-stroke oil is less expensive then dfi 2-stroke oil. 4-strokes only require oil when it is time for an oil change, which is typically once a year, unlike 2-strokes that will require addiational oil throughout the season.
Don't let the thaught of cost or labor of and oil change on a 4-stroke outboard frighten you. I have a 140hp suzuki and it is less expensive to change the oil in it as it is in my v6 pickup, and I can purchase everything I need to do it at any local autoparts store.
There are a number of good 4-stroke engine oils on the market Mobil, valvoline, and Castrol GTX to name a few, as well as good aftermarket oil filters such as, wix and fram.
Edited by triumph190 (09/08/08 05:52 AM)
Edit Reason: spelling