Understanding Fuel Octane Numbers (RON) and Which Fuel To Use on Your Car

The initials RON refers to Research Octane Number, and this is a standard measure of the fuel’s ability to withstand compression. According to industry standards, every car will have its particular requirement for the fuel, and this will be determined by the use for which the car was made in the first place. If the car was made to be a high performance vehicle, then its octane requirement will be high and if it was made to be a regular convenience car then its octane requirement will be lower. These octane figures, which I will describe in detail shortly, can be found at the back of your vehicle’s fuel lid cover, the car’s manual or by contacting the car’s dealership.

RON 87, RON92, RON95, RON97 – What’s the Difference?

Having understood that the higher the octane rating then the greater the ability to withstand compression, we will first look at what compression means. In a petrol engine, fuel is mixed with air and then ignited together to deliver power, which differs from diesel engines in which only air is compressed and then fuel is injected into the compressed air. Compression therefore is the pressing of air or the fuel/air mixture in an engine’s combustion chamber, and the result is tension and heat. An engine therefore produces power when a spark is delivered to this highly pressurized mixture, the whole process being referred to as combustion and that is how an engine ought to work to propel the vehicle forward or backwards. Sometimes, however, the pressure and heat from the compression is too much that the fuel may self ignite before the piston reaches the end of the compression stroke, (it is only at this point that a spark is issued by the spark plugs to induce combustion) and even if it doesn’t ignite prematurely, a phenomenon technically known as detonating, then it will have undergone so much pressure than when the spark is finally issued, instead of burning normally it is going to explode. When this happens, unfortunately, most of the engine components will get damaged, which might even lead to the engine knocking, and to repair this or replace the entire engine is a costly affair. The numbers indicated by RON therefore mean that the higher the number the more resilient the fuel will be against detonating. But unlike popular belief, it does not mean that fuel with a high octane rating such as RON99 will deliver more power; high performance cars use fuels with higher octane numbers because the compression within their combustion chambers is so much that fuel with a low octane rating, RON87 for instance, will most likely detonate and thus deliver less power as well as damage the engine.

Supposing My Car’s Fuel Requirement is RON87. Can I Use RON99? What Will Happen Then?

Yes you can. The only thing that might happen as a result is that your fuel bills will hit the ceiling and you will end up with an emptier wallet because the higher the octane rating the higher the price of the fuel. In regards to engine power, however, nothing will happen as a result. Every car is made for a specific buyer and someone buying a utility car is not looking for pleasure or speed, and car manufacturers know that. This is manifest in every car’s design language, from the materials on the seats to those used on the dashboard and instrument panel, from the body styling to the rim type and size, from the engine size to the exhaust sound, from how and where the car is marketed and ultimately to the type of fuel it will use. Why would you want to suffer the financial implications that befall people driving sport cars while you drive a convenience hatchback anyway?