Let’s cut right to the chase, Ethanol in gas is a problem when storing a boat. There are several considerations and decisions you need to make.

1) Should you be adding something to the fuel to help prevent against the problems caused by ethanol (phase separation, sludge build up, water in tank)?

2) The second decision you need to make is whether or not to leave your fuel tank empty or full when storing your boat? Which is better?

Let’s tackle the first question – “Fuel Additive!” “Phase Separation” What is “Phase Separation?” It is what happens to the ethanol in gas when it just sits there for long periods of time (approximately 90 days). You can see a visible separation between the gas and the ethanol (E10), and if left there will form a sludge that deposits itself on the bottom of the fuel tank in the form of a orange gel-like substance. This happens because ethanol is “hydroscopic” and attracts water from air. This is what creates the visible layers you can see in the fuel. It is this combination of fuel, water, and E-10 that cause the sludge like gel to form and increases the chances of your motor running poorly or not at all.

From what I have experienced, working at a marina and being a boat owner for 7 years and having boats in the family for over 20 – The answer is a clear “YES!” A good fuel additive certainly can not hurt and will help with this rapidly increasing problem. The product I recommend to people is Star Tron (manufactured by Starbrite). This additive prevents and reverses E-10 ethanol enhanced gasoline problems. It also treats water in the fuel tank, and much more. StarTron uses an enzyme treatment formula that eliminates the microbial growth in the fuel as well as overall cleaning. So you may want to pick up or order a bottle of this stuff. A good fuel additive should last up to a year in your fuel system. REMEMBER – this helps with the fuel treatment & ethanol problem only, you will still need a good fuel conditioner or stabilizer when storing your boat.

On to question #2 (Storing your boat full of fuel or empty?). This one is a bit tougher than the first question. The answer appears to be - store it FULL of fuel. You have to ask yourself, Is it going to cause my boat more damage storing it empty or full of fuel? Here is some information and research that has been done to help you make this decision….

According to the National Fire Protections Standard for Marinas & Boatyards (2006), Chapter 7 Berthing & Storage/Dry Storage subsection 7.2.1.5 (4) - If you store it empty, you run the risk of fuel vapor ignition, “Permanently installed fuel tanks shall be stored at least 95 percent full.”

When you store your boat full of fuel - (phase separation) begins after 90 days (maybe even sooner). Therefore, a good fuel additive can practically eliminate this problem and help with any harmful vapors that may occur.

According to an article that was posted on Mercury Marine last year, “Is there a simple solution to water condensation in the tank as a result of ethanol? It is best to maintain a full tank of fuel when the engine is not in use. This will reduce the void space above the fuel and will reduce the flow of air in and out of the tank with changes in temperature. This will reduce condensation on the internal walls of the tank and will limit exposure of the ethanol in the fuel to humidity and condensation.”

According to the MMTA, they stated “E10’s limited shelf life of 60-90 days (after which there is a high likelihood of phase separation), has led some marine engine manufacturer’s to recommend that boats intended to be stored for over 30 days be stored with empty gasoline tanks.”

One of the dangers that are inherent with storing any large quantity of fuel is the possibility of gasoline vapor accumulating and being potentially explosive. Does this out way leaving your tank empty and susceptible to water, condensation, or fuel vapor ignition?

In conclusion, if you take into consideration the damage that can be caused by leaving your tank full or empty, full seems to limit that amount of potentially harmful and hazardous effects. The decision is going to be yours, however my boat will be full with both a fuel additive and fuel conditioner added (run through the engine) before storage. Please continue with your research before you make a decision.

Hope this helps – LunkerUSA.com Team