Some fuel additives do what they say on the bottle but the ones claiming more performance or fuel efficiency…there’s next to no evidence to support the claims.

Updated 22 September 2022

Marketing people get paid a lot of money to hype new products…they’re careful at walking the tightrope between truth and lies, and words like ‘may’ or ‘might’ are the get out of jail cards.

See, if you believe the hype then fuel additives can do everything from boost the octane rating of your fuel to cleaning the engine, to removing water from the fuel to cleaning injectors and on and on the list goes. But, as Public Enemy said, ‘don’t believe the hype’.

Following the manufacturer’s instructions should see these products cause no damage to your fuel system and engine, but whether they’ll make a noticeable difference in a once-off application is another thing. And you wouldn’t want to make up your own cocktail and tip half-a-dozen bottles of the stuff into a tank of fuel as that will seriously compromise the chemical structure of your petrol and likely to do more harm than good.

While the motoring club, RACV admits these products do work, just how well they work will depend entirely on the magnitude of the problem; with more drastic intervention required (replacement of the fuel injectors or intake valves) if the issue is serious enough.

However, if you own a newer car, and I’m talking something less than 10 years old then adding all these cleaners and what not are generally not going to do much at all. Really, they’re designed for higher mileage cars that might have missed the odd service schedule.

It’s worth noting that car manufacturers don’t support or recommend the use of fuel additives. Rather they suggest sticking with the manufacturer service schedules, using the recommended fuel grade, and keeping your car in good running order.

That said, some additives, like those designed for diesel engines driven in cold climates where diesel can gel and you haven’t filled with Alpine Diesel, can be a necessity. And like a car battery, memory minder, or a multi-stage charger being used to keep a car battery topped up when not being used for a long period, some additives are designed to ensure your fuel doesn’t go off when left standing for very long periods of time.

So, what about those that claim to boost performance or octane ratings? Well, there have been plenty of tests into the use of octane boosters and every single test has failed to find any boost in either the fuel’s octane rating or performance. So, you’ve probably got to ask yourself if you believe science or your next door neighbor on this one.

And then there are some that claim to clean your engine. Well, given that most fuels have to contain a ‘certain amount’ of ‘cleaning agent’ adding engine cleaner is probably a waste of money. That said, that is likely true if you live in the UK, US or Europe but given we don’t really know the levels of cleaning agent included in fuels (both low- and high-RON) in Australia it’s hard to say whether it’s cheaper to buy a bottle of cleaner as opposed to filling up with a high-octane ‘dirt-busting’ fuel.