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Fuel stabilizer — how it works

Fuel stabilizer — how it works

Why does gasoline need fuel stabilizer?

All gasoline goes bad when it’s exposed to the air, heat, and water.

How does air get into your gas tank?

All gas tanks have some amount or air at the top, even when full. As the engine pulls fuel from the tank, the gas cap lets in outside air to replace the depleted fuel. Otherwise the tank would collapse as its sucked dry.

How does water get into your gas?

All air contains moisture. As the air and fuel heat up and cool down, the moisture in the air condenses on the sides of the tank and drips down into the gas.

How does air cause gasoline to go bad?

Air degrades gasoline two ways:

Evaporation —Air and heat cause the lighter volatile compounds in gasoline to evaporate away, leaving only the heavier less-volatile components. Those heavier components are harder to vaporize and ignite, causing hard-starts, no-starts and engine performance issues.

Oxidation—Oxygen in the air reacts with hydrocarbons in the fuel, transforming them into insoluble solids, called gum and varnish. The solids fall out of suspension and stick to the metal surfaces in the vehicle’s fuel and intake system. The sticky solids clog small fuel passages and intake valves, causing no-starts/hard-starts, poor performance, misfires, and sticking valves.

Oxidation also reduces the fuel’s lubricating qualities, thereby causing accelerated valve and cylinder wear.

How does water affect your engine?

Water is heavier than gasoline (~8.3-lbs/gallon for water versus ~6.07-lbs/gallon for gasoline) so it falls to the bottom to the bottom of the tank. Since water isn’t combustible, you wind up with no-starts, hard-starts, and poor performance. In cold weather, the water freezes, blocking fuel flow. Water also causes tank, fuel line, carburetor and fuel injector corrosion and damage.

What is phase separation?

Ethanol fuel is a blend of gasoline and ethanol. Ethanol is hygroscopic, which means it absorbs moisture from the air in the tank. But there’s a limit to how much water ethanol can absorb. At around 0.5% water absorption, the ethanol and water separate from the gas and falls to the bottom of the tank; causing all the no-start, hard start and performance issues listed above.

What does fuel stabilizer do?

Fuel stabilizer, depending on the formulation, tries to reduce the evaporation of the fuel’s light volatile components, reduce fuel oxidation that causes gum formation, slow phase separation, and dissolve any gum and varnish that has accumulated in the fuel system.

How do fuel stabilizers work?

There are three types of fuel stabilizers: floating seal, emulsifying, and encapsulating. Here’s how they work and the pros and cons of each.

How floating seal fuel stabilizers work

Floating seal fuel stabilizers attempt to reduce oxidation and moisture infiltration by floating a layer of light petroleum distillates (similar to kerosene) on top of the fuel.

This method isn’t fool-proof. For example, it can’t prevent moisture condensation on the side of the tank (which is the most common way for water to enter the fuel) from dripping down into the fuel. It can’t prevent oxidation and moisture infiltration while the tank is in motion (any break in surface tension allows the fuel to contact the air in the tank). Lastly, the floating layer itself is subject to oxidation and gum and varnish formation because it too is a petroleum-based product.

Which products are floating seal stabilizers?

According to the manufacturer’s Material Safety & Data Sheets:

Sea Foam’s active ingredient is petroleum distillate, making it a floating seal type stabilizer.  Sea Foam also contains a hydrocarbon-based solvent as a cleaning agent to dissolve gum and varnish. Finally, it contains isopropanol (rubbing alcohol), which makes up less than 25% of the mixture. Isopropanol is a solvent and a drying agent used to absorb water.

Sta-Bil’s active ingredient is hydrotreated light distillates (95% of the mixture), making it a floating seal type stabilizer. In addition, Sta-Bil also contain <10% ethylene glycol monobutyl ether which is a surfactant that lowers the surface tension of the product, allowing it to maintain a floating seal.

The pros to the petroleum distillate method of fuel stabilization

• Floating petroleum distillates on top of the gasoline provides some protection against evaporation, oxidation, and phase separation as long as the “treat rate” is high enough to coat the entire surface area of the fuel and the fuel remains still in the tank (not sloshing around). So it works best when the engine isn’t in use or the fuel sits in a storage tank.

The cons of the petroleum distillate method of fuel stabilization

• The petroleum distillate method relies on distillate’s surface tension to maintain a continuous layer of the distillate “seal” across the surface of the fuel. Unfortunately, fuel slosh breaks the surface tension while mowing, weed whacking, chain sawing, etc. The churning fuel then mixes with the air and moisture, causing oxidation, gum and varnish formation, evaporation, and phase separation. In other words, the floating layer works when the fuel is still, but not as well when the fuel is in motion.

• This floating seal method offers no protection against the moisture condensation that forms on the sides of the tank. That water bonds with the ethanol in the tank, phase separates and then falls to the bottom of the tank.

• The petroleum distillate itself isn’t immune to the same type of oxidation and gum and varnish formation that affects the gasoline. So the air in the tank attacks the floating petroleum distillate layer as well, diminishing its ability to protect the gasoline and causing its own gum and varnish formation.

• Floating seal fuel stabilizers must be added to fresh gas in order to protect it from oxidation and evaporation. It can’t “fix” stale gas after the fact. However, the cleaning agents in these floating seal stabilizers can dissolve some of the gum and varnish that’s accumulated in the system.

How emulsifying fuel stabilizers work

Emulsifying fuel stabilizers combat phase separation by emulsifying the water/fuel mixture. The emulsifying agent breaks the water molecules into smaller droplets and suspends them in the fuel so they don’t settle to the bottom of the tank. So you wind up with an homogenized blend of oxidized fuel with suspended ethanol/water and gum and varnish components. In addition, some of the emulsifying stabilizers use a light petroleum distillate to float on top of the fuel to reduce oxidation.

Which products are emulsifying fuel stabilizers?

• Star Tron Enzyme Fuel Treatment is an emulsifying fuel stabilizer that, according to Star Tron, “…helps prevent phase separation by dispersing water throughout fuel as submicron-sized droplets.”  Star Tron Enzyme Fuel Treatment contains 90-95% hydro treated light petroleum distillates as a floating seal and, Kerosene 1-10%, and hydrodesulfurized Keosene 1-10% as emulsifiers.

The pros to emulsifying fuel stabilizers

They prevent phase separation, so you’re less likely to wind up with a layer of ethanol/water at the bottom of the tank. But they do so by suspending the water in the fuel.

The cons to emulsifying fuel stabilizers

The emulsification process actually creates a degraded fuel that’s not as volatile and is still corrosive to the fuel system.

How encapsulating fuel stabilizers work

Rather than try to fight the never-ending battle of water in the fuel, encapsulating fuel stabilizers deal with the water by encapsulating it in a flammable “shell.” Unlike emulsifying stabilizers that produce a degraded water laden fuel, encapsulated fuel burns every bit as well as fresh out-of-the-pump fuel.

Encapsulating fuel stabilizer, like emulsifying stabilizers, breaks the water into micro-sized droplets. It then bonds the water droplets with a flammable shell that helps it burn when it’s finally atomized by the carburetor or fuel injector.

Which products are encapsulating fuel stabilizers?

K100 Fuel Treatment contains burnable organic compounds that encapsulate free water. The formula also reduces oxidation to prevent gum and varnish formation. In addition, K100 contains cleaners to dissolve and neutralize existing gum and varnish deposits. The alcohols in the formula actually increases the fuel’s octane ratings by 1-1/2 to 2 points.

Other fuel stabilizers only work when added to fresh gas. They can’t “bring old gas back from the dead.” K100 Fuel Treatment can reverse phase separation and can dissolve gum and varnish deposits in the fuel system. So it can be added to “old stale gas.”

The pros of an encapsulating fuel stabilizers

• Eliminates phase separation
• Reverses phase separation
• Enhances the combustion process by coating the water molecules with a flammable shell
• Reduces the freezing point of the fuel (-70°F)
• Not petroleum based
• Includes a lubricant
• Includes a cleaner to deal with gum and varnish. Dissolves gums and varnishes
• Increases octane ratings 1-1/2 to 2 points
• Eliminates corrosion and formation of acids
• Reduces paraffin formation in winter
• Increases octane ratings 1-1/2 to 2 points

©, 2022 Rick Muscoplat

Posted on by Rick Muscoplat


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