Manufacturers make many claims for fuel additives such as being able to transform an old engine into a smoothly running one or that they will result in using less fuel. A fuel additive can be added to petrol or diesel engines that will clean injectors and valves and keeping carburetors operating efficiently.
After using these additives the car should run more smoothly, offer more efficient fuel use, reduce emissions and improve the car’s performance over time.
While fuel additives can help an engine’s performance in specific circumstances, experts say that those that claim to improve fuel economy are likely to be ineffective and any savings you may make will be less than the cost of using the additive in the first place. Cars that are less than 10 years old do not require additives since they are already optimized for fuel efficiency and their engines are still relatively new.