Additives are used to preserve the engine over time and improve its operation. There are various types of additives based on the type of engine.
For example, they are on the market:
Cleaner additive for the injectors to clean up deposits and improve operation
Additives for non-catalyzed cars that perform the lubricated function that lead contained in super petrol had
Cleaners for diesel engines to eliminate paraffin and traces of water in diesel
Additives for classic cars
Cars of yesteryear used gasoline with lead content which served as a lubricant for cylinders and valves. Today, to keep these engines active, there are special additives to be added to unleaded unleaded petrol.