That's not what I said Gary. I did not say run wide open for 14 hours. you may spend time on them but, you really have no idea what you're talking about. I can promise that these motors are more fuel efficient than almost every outboard and inboard out there. I don't know why I'm arguing with you, in your little world your right. But you couldn't be further from the truth. Before shooting your mouth off. Do me a favor. Go top your boat off, run your boat wide open for 20miles, go back to the ramp, put it on the trailer go straight to the gas station and fill up again. What I can promise you is this, if you have a 6 gallon gas tank... Make sure you have cell service to call a friend to tow you back to the ramp, cause you will be out of gas at about the 13-15 mile mark. From the pictures you've posted it appears you have a early 70s model Mercury between 25 and 40 horse had a very similar motor 6 gallons of gas would not give me 15 miles up river. My 87 Johnson was around 3miles per gallon wide open. In Case you didn't realize how to measure mpg on boat. Run it wide open for an extended period of time that's how you actually test fuel efficiency in boats.
This is why I rarely get in here anymore, people with little to no experience, give poor inaccurate advice on topics with no factual knowledge of a subject.