Quickleen does nothing to stabilize the fuel. It cleans the fuel system and removes/prevents carbon build up which is a big killer for 2 stroke engines. According to the Mercury guru on Bass Boat Central it should be used at EVERY fill up. When I first started using it (on a carb'd Mercury 115), a lot of black gunk (carbon) was coming out of my exhaust plus it started easier and idled smoother after a tank or two.
I use my boat regularly and to be honest, I do not know if I need to stabilize the fuel. To me, it is insurance to prevent having fuel related issues. I'd rather be safe than sorry and Startron is not expensive.
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