Fuel Additives for Outboards

No matter which additive you choose, protecting your fuel system is a good investment

Many articles have been written over the years about ethanol and why the government has mandated its use. This is not another one. Instead I would like to talk about ways to combat the harmful effects of ethanol in gasoline by stabilizing the fuel/ethanol/water mix in your fuel tank by the use of a fuel additive.

Since its introduction into gasoline, ethanol has wreaked havoc on the fuel systems and engines on many a vessel. The main reason has to do with the conditions that a boat is operated in. The more moisture that is present in the atmosphere, the more water can be absorbed by the ethanol. When the ethanol/water combination reaches a certain level, the ethanol and water mix “drops out” of the fuel to the bottom of the tank, commonly referred to as fuel phase separation. The environment a boat
is stored in, the length of time it remains static and abrupt temperature changes are factors in when the separation may take place. Since the fuel pickup is on the bottom of the tank, the ethanol/water sludge enters the fuel system and can clog your fuel filter. It can also adversely affect your engine’s performance by lowering the fuel’s octane rating plus clog carburetor jets and fuel injectors.

The cleaning properties of ethanol can loosen varnish and corrosion deposits, in the fuel tank, which then travel through your fuel system. It doesn’t take much to impede an injector’s ability to atomize fuel. Anyone who has tried to use a can of spray paint understands how easy it is to disrupt a spray pattern. For an engine to run smoothly and efficiently, the injector must produce a consistent and even spray pattern of fuel.

There are several fuel additives available today and most are excellent for both 2-and 4-stroke engines. An additive can do more then just prevent fuel phase separation. They clean your entire fuel system, including carburetors and injectors, plus prevent corrosion. If you break down the cost of adding an additive to your gasoline with each fill-up, it’s much less than constantly replacing fuel filters, outboard repairs or worse yet, towing bills.

How do they work? Without out getting too technical, additives help fuel to burn more completely, which increases performance and reduces carbon deposits. They also work as a dispersing agent for any water present in the fuel, reducing the droplets to sub-micron size. The suspended water is safely eliminated under normal engine operation. The regular use of an additive will further assist in keeping fuel injectors and carburetors clean. It also allows you to run fuel through your motor that contains ethanol without any ill effects.

Now, fuel additives can only go so far. They can’t solve poor gasoline quality problems. Bad gas is just that, bad, and should be replaced if you suspect that it has been sitting in the tank for an extended period of time. Once phase separation has occurred in fuel, it cannot be reversed.

Fuel additives aren’t just for 4-stroke engines. If you are running a 2-stroke outboard, you can buy oil that combines a TC- W3-spec oil with a fuel stabilizer, ethanol treatment and engine cleaner.

An “All-In-One” 2-cycle engine oil combines all of these ingredients in the proper amounts so you don’t have to measure and mix each one individually. It’s also less expensive than buying the oil and fuel treatments separately. In the case of an oil- injected outboard, that uses a remote oil tank, you still need to treat the fuel in the tank individually.

One misconception is thinking if you only run non-ethanol fuel in your boat you won’t have to worry about water issues. Unfortunately that’s not true. Condensation, a leaking gas fill, misaligned tank vent and poor quality fuel, right from the gas station, all contribute to fuel problems.

The reality is that most boats are at rest for much longer periods than they are in use. Even good quality fuel can go bad in as little as two to three months if not protected. A fuel additive, or 2-stroke oil with an additive, can keep your gasoline stabilized for as much as two years plus add a layer of protection for your engine and fuel system.

Below is a list of companies that produce fuel and oil additives:











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