Boat Maintenance

Marine Fuel Additive – Explained By Experts

A recreational boater contemplating fuel additives for his gasoline-powered craft is faced with a daunting range of choices.  There are products for fuel stabilization and off-season storage, products for cleaning up dirty engines, and others that claim to eliminate the hazards of ethanol-based fuels by “removing” water from the fuel system.  With retail shelves often displaying dozens of products making a range of claims, it may make it challenging for boaters to navigate the clutter and figure out which product will best suit their needs.

Here are some straight facts on common marine fuel additive terminologies, as well as what scientifically proven marine fuel additives can actually do for boaters:


Approximately 98% of gasoline in the U.S. contains some amount of ethanol (alcohol made from corn/plants), with the most common blend at pumps being E10 (10% ethanol/90% gasoline).   This generally isn’t problematic in automobiles, where fuel is cycled rather quickly.  In boats, however, that ethanol-based fuel often sits for long periods of time in hot, wet environments and can lead to the formation of water in the fuel system.

Water in the fuel can cause a variety of problematic issues for boat fuel systems, including corrosion, poor performance, and even engine damage.


Phase Separation

When there is enough water in gasoline, it can “separate” and form a definitive layer at the bottom of the fuel tank (as water is heavier).   The true solution to this is to prevent water from accumulating in the first place, by practicing proper fuel system “behavior.”  This includes: keeping your gas tank full between uses, making sure your fuel fill cap and vent lines are in good working order, installing a water-separating fuel filter and changing it when needed.

A fuel/water separator is the best defense against water in your fuel.

“Water Removal”

“We employ the best fuel scientists in the world, and they will tell you that there are no solvents that can remove water from fuel in the manner described by these additives,” said Joe DeFina, Chevron’s Global  Fuel Additives Manager.  Instead, formulas that claim to “remove” water actually use emulsifying chemicals that blend separated water and fuel back together.  This makes it look as if the water has disappeared if you’re watching a video demonstration online — but it’s still there, and now you’re actually going to run that water through your engine rather than filtering it out as is recommended by manufacturers.  And, as we explained, water in the fuel system can cause a variety of problematic issues including corrosion, poor performance, and over time, even engine damage.

Detergency& Engine Cleaning

 Keeping the fuel system and engine clean is an important task of marine fuel additives.  When you run a boat hard and shut down to fish and do this over and over, impurities in gasoline get “baked” to form deposits on valves and particles that impede the flow of fuel through injectors.  Detergents, of different qualities and levels, are added to gasoline to remove and control deposits; however, carbon deposits still accumulate over time – and more so with lower quality fuels.

This is where aftermarket fuel additives and their concentrated detergency come into play.  Polyether Amine (PEA), for example, is a powerful detergent that has enabled Chevron to provide the unsurpassed cleaning power of Techron. PEA was invented by Chevron in 1980 to clean engines and remains the optimum proven cleaning agent. There are various types of PEA chemistry in the market and they are not all the same.  Less costly PEA detergents used in some additive formulas can cause problems in your crankcase. That’s right, inferior fuel additives can make their way into the crankcase and cause sludge and varnish.

It’s important to select a quality additive that is designed specifically for your application.

Corrosion Protection

Boats are stored and used in wet, corrosive environments — and this can lead to problems for fuel system components in marine engines.  A good marine fuel additive should provide strong corrosion protection for boats used in both fresh and saltwater.

ASTM International is a standards organization that develops and publishes testing guidelines. When products are tested according to ASTM methods, consumers can compare product performance across manufacturers, knowing that it is an “apples-to-apples” comparison. Chevron uses ASTM test methods, and Chevron’s ASTM testing has demonstrated that there are several fuel additives on the market that perform worse than base fuel (gasoline with nothing added) when it comes to corrosion test results in saltwater conditions.  This is likely a result of chemicals in their formulas that allow the fuel to hold more dissolved water.  Consider the corrosion protection levels of any marine fuel additive before you use it – especially if you use your boat primarily in saltwater.

Fuel Stabilization

Stabilizing fuel refers to preventing oxidation and the reduction of its octane rating.  Low octane fuel can result in engine knocking and damage your engine. Modern engine control systems can compensate for some loss in octane, but this reduces engine power and efficiency.

Oxidation is the process that causes varnish and gums to form in stagnant fuel. Once formed, gum and varnish can clog your fuel system. Varnish and gum can result in restricted injectors and gummed up carburetors, or even clog up the system badly enough to cause a fuel pump failure.

This is important when a boat sits for extended periods of time between trips, or especially when “winterizing” a vessel and storing it until the next boating season.  Marine fuel additives usually offer a stabilization time period for which they can keep the fuel “fresh” and prevent oxidation and octane breakdown. The best performers can stabilize fuel for up to 24 months.

“Managing your boat’s fuel for strong engine performance, reliability and trouble-free time on the water may seem complicated — especially when faced with such a wide range of products.  It’s actually fairly simple,” said DeFina.  “Treat your fuel with a proven additive that does not contain emulsifiers or alcohols that contribute to water uptake.  Make sure your boat has a water-separating fuel filter, inspect it regularly and change it when needed.  Keep your fuel cap tight and make sure your vent lines are in good shape.  Lastly, when you are going to store your boat for a while, fill the tank, dose it with additive and run it through the engine before storage.”

Techron Marine Fuel Treatment was designed for any gasoline-powered boat.  When used with every fill-up, it is proven to prevent fuel-related issues, provide the highest level of corrosion protection in fresh and saltwater, and keep engines clean and running at peak performance.   It is also laboratory proven to deliver fuel stabilization for up to 24 months for extended storage.  For more information and availability nationwide, visit