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What Do Fuel Additives Really Do?

Fuel pump

You’ve probably seen the significant shelf space devoted to fuel additives and wondered what, exactly, all those bottles actually do. The answer is a broad one, because different types of additives are designed to offer unique benefits — while some are more like the automotive equivalent of snake oil. Knowing the difference can save you money and keep your vehicle running strong, even as you pile on the miles.

Fighting Engine DepositsEngine

The majority of fuel additives are advertised as cleaners for your engine. More accurately, they are intended to reduce the effects that fuel deposits — such as carbon — can have inside your motor’s combustion chamber as they build up over time. Some might get more specific and target fuel injectors, with the intention of removing any gum that could accumulate from ethanol or impurities in your fuel.

Do they really work? It depends on what your expectations are. It’s unlikely that you’ll see a huge boost in power or fuel efficiency after dumping a single bottle of fuel cleaner in your tank —  but this type of additive isn’t going to cause any harm, either. This is truly a case of “your mileage may vary” depending on the actual condition of your engine.

Helping Diesels Through the Winter

Low-sulphur diesel fuel doesn’t play nice when the temperature drops. If you live in a colder part of the country and drive a diesel vehicle, you’re probably aware of how much of a hassle gelling can be. There are a number of fuel additives out there designed to prevent the low-temperature gelling of diesel fuel, keeping it from clogging fuel filters and ensuring easier starting during the winter.

Keeping Fuel Stable Over Time

The final common type of fuel additive is a stabilizer. Fuel stabilizer is intended to prevent gasoline from separating into water and its component chemicals when stored over a long period of time (typically six months to a year). Adding stabilizer to a tank of gas is a good idea whenever you store a vehicle for that period of time, as “bad gas” can lead to corrosion, fuel system clogs and poor performance once you start the engine up again.

It’s always a good idea to make sure you actually need a fuel additive before picking one up and adding it to your fuel tank.

Check out all the chemical & lubricant products available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on fuel additives, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Morguefile.


Benjamin Hunting View All

Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States. Over ten years of racing, restoring, and obsessing over automobiles lead me to balance science writing and automotive journalism full time.  I currently contribute as an editor to several online and print automotive publications, and I also write and consult for the pharmaceutical and medical device industry.

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