100th gasoline instead of 92nd and 95th: harmful or not? The engineer answers

Modern fuel is designed differently than before

Gasoline today and gasoline twenty years ago are different things. Previously, the desired octane number was obtained using additives, many of which were harmful to the environment. A classic example is tetraethyl lead: effective but toxic. In this case, different brands of gasoline could be produced on the basis of completely different additives.

It's unified today. Modern gasoline is brought to the desired octane with alcohols and esters. The simplified process looks like this: after hydrocracking, a base with an octane number of about 80 is obtained. It's got additives -- less for '92, more for '95, more for 100. In fact, the technology is the same, and the difference is only in the number of additives. This is the key to understanding.

Carburetor machines 100th contraindicated

In old cars with a carburetor, the fuel mixture was prepared mechanically. No sensors, electronic nozzles and catalysts were there - the design is inflexible. If it's set to 76, that's where it should work.

Pour the 93rd - the mixture will not have time to completely burn in the cylinder, and the burning residues will come out on the exhaust stroke, melting the valve and the block head. And the 100th in that car will burn the valve in just one average trip. The same rule applies to the first generation of injector – mono-injection. If the instructions say 92, then only 92.

Modern engines adapt to any octane

Cars with EURO 3 or higher standards are computers on wheels. The pump in the tank supplies fuel to the nozzles, and the electronic control unit, based on the readings of the sensors, decides when and how much to inject. The operation of the motor is monitored by lambda probes before and after the catalyst, detonation, temperature, revolutions and speed sensors.

Manufacturers often write directly on the gas tank hatch: gasoline from the 92nd and above. That’s 92, 95, 98, 100, and nothing happens. Electronics quickly adjust the injection. The 100th is filled - it needs less, otherwise it will not burn. The nozzle opens for a shorter time: the power slightly increases, the flow rate falls. The 92nd was filled instead of the 95th - the system will supply more fuel so that the power does not subside, and the consumption will increase slightly.