I personaaly have never delt with that shop, But mercruiser has sent out a few service bulletins regarding gas. They say it will lose its octane in only a few weeks. Also, it only takes a little drop of water in the gas to make a motor sputter and die. If you have ever filled up while in a marina, I guarantee you took a little bit of water. Water in the gas and one season old fuel are both bad news, especially if you are running a high perf motor. Its Only my opinion, I am sure you will get more of them.