Just a quick note while you're looking for the model number.....TCW-III is exactly what you want to use on any outboard from the 50's up that is 2-stroke in the smaller horsepower motors at least. How much of it is the question, and as Cattrans. said, can only be answered if you know exactly what you have. Basically, if the motor is stock and has the 2-line/3prong fuel line connector, it uses 24:1, if only the 1-line/2prong connector, then 50:1. IF you tell us what motor you have, we might be able to make some other suggestions that would be helpful as well, since this motor is new to you. BTW, iboats sells manuals if you're interested.