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NAPA Experts: When to Add Gasoline Additive & How

NAPA Experts: When to Add Gasoline Additive & How

You’ve probably seen bottles of gasoline additives on the store shelves at your local NAPA Auto Parts store. They come in all shapes, sizes and colors. Obviously, these automotive fluids must serve some purpose or else nobody would buy them, but how do you know when to add gasoline additive to your fuel tank? The answer depends on your vehicle and your situation, but our NAPA experts are here to walk you through it.

Picking the Best Gasoline Additive

There isn’t just one gasoline additive; each type is designed for a special purpose. There are actually additives put in gasoline from the refinery process. But you can also tweak your own gasoline mix with one of these common options.

Fuel System CleanerUsing Sea Foam fuel treatment

Your fuel filter does a great job of catching physical debris that enters the fuel system. But what about the stuff that is dissolved in the liquid fuel itself? Or the stuff that clings to the inside air passages of your intake system? A fuel system cleaner (like Seafoam gasoline additive) dissolves gunk that coats intake valves, intake passages, cylinder heads and other air paths where fuel is introduced. Because the fuel system cleaner is carried through the engine via the fuel, only areas that come in contact with fuel are cleaned. You can use a fuel system cleaner any time of the year.

Octane Booster

At the fuel pump, you normally have a choice of three octane levels: 87, 89 and 93. Most vehicles on the road run just fine on one of these octane amounts. Your normal commuter car can probably use any of the three, but a high-performance engine usually requires a higher octane level. While modern ignition timing wizardry can help keep knocking at bay, it can’t change the physical compression ratio of the engine. Using a fuel that is below the octane rating requirement for your engine can lead to damage.

If you find yourself without a high-octane option or accidentally put lower octane fuel in your sports car, there is a solution: octane booster. Octane booster won’t magically make your car faster, but it will allow an engine tuned for high octane fuel to perform at its fullest. If your engine demands high octane fuel with risk of damage without it, you might want to keep a bottle of octane booster in the trunk just in case.

Fuel Stabilizer

Most people don’t know that fuel has a shelf life. Gasoline that is left to sit for long periods of time can separate because it is made from a blend of chemicals. Water that was suspended in the fuel separates and collects in the fuel tank, possibly leading to corrosion. Using fuel stabilizer helps keep everything mixed correctly. Things like collector cars and lawn mowers that sit during winter months, or any other gas-powered engine that sits for months on end, should definitely have their fuel treated with gasoline storage additive. When people talk about gasoline additives for lawn mowers, fuel stabilizer is usually what they mean.

Lead Substitute

If you have an older vehicle made back when leaded gas was around, the engine was likely engineered to need that lead in the fuel. Obviously lead in gasoline is bad, so it isn’t around anymore (unless you fly a plane), but there are still plenty of old engines left. You can rebuild the engine and use modern materials that are designed for unleaded fuel or just use lead additive for gasoline. Adding lead additive to gasoline gives similar protection as the old leaded gas, but without the detrimental environmental effects. You must add it to every tank of gas as the effects are not permanent.

Winter Gas Additive

When the weather turns, bad things can happen to your fuel system. That’s why there are gasoline additives for cold weather. If your fuel has absorbed water, that water can actually freeze up as the temperatures plummet. Products like HEET gasoline additive absorb water from the fuel and isolate it to prevent freezing. The best time to use a winter gas additive is before extremely low temperatures settle, so get ahead of the problem in late fall if possible. That way any water in your fuel tank is gone when the snow starts to fall.

Diesel Fuel Anti-Gel Additive

We’re mentioning this one because gasoline additives and diesel additives are sometimes tossed around as the same thing. While diesel is an amazingly efficient engine fuel, it has one odd quirk: it can turn into a gel in extreme cold weather. Diesel fuel contains paraffin wax, which during normal weather conditions stays in a liquid form. But when temperatures drop below freezing, the paraffin starts to come together and solidify. If enough paraffin clumps together, it can block fuel intake ports, fuel filters, fuel lines and even injectors. Diesel powered vehicles in extreme climates, where sub-zero temperatures are common, actually use heaters (like a block heater) to keep diesel fuel liquid. However, for most people, the simplest solution is adding anti-gel diesel fuel conditioner during the winter months.

How to Add Gasoline Additive

If you have ever filled up the fuel tank on your vehicle, you are already qualified to add gasoline additive. Wait until your gas tank is at roughly ¼ full. Pick up the gasoline additive of your choice by shopping at Read the instructions on the additive bottle to find out how many gallons of fuel it will treat. Consult your owner’s manual to find out how many gallons of fuel your vehicle tank holds. Usually, the bottle of gasoline additive will treat an entire tank of fuel, but if you have an extra-large fuel tank in a truck or SUV, you may need two bottles.

Open the gas cap and pour the additive in your tank. You may need to use a funnel to prevent spilling. If any additive spills, wipe it up immediately to prevent possible damage to paint. Once the additive is in the gas tank, fill up the tank with gasoline to mix it thoroughly. Now it’s time to Get Up & Go!

Your local NAPA Auto Parts store carries all the best gasoline additives for your sedan, truck, van, SUV and even lawn equipment. When you shop at a participating NAPA Auto Parts store or on, you can earn NAPA Rewards. Sign up for a free account today and earn 1 Point for every $1 dollar you spend. Earn 100 Points to get $5 off your next purchase!

Featured image courtesy of Pixabay.

Brian Medford View All

With an automotive writing career spanning over two decades, Brian has a passion for sharing the automotive lifestyle. An avid DIYer he can usually be found working on one of his many project cars. His current collection includes a 1969 Olds Delta 88 convertible, BMW E46 sedan, and a slant-6 powered 1975 Plymouth Duster.

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