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You might have seen numbers like RON97 and RON92 at your neighborhood petrol station. Fuel with a RON97 rating is more expensive, RM1.92 per litre at time of writing with the lower RON92 rating going for RM1.88. Have you ever wondered what they mean? Why is RON97 more expensive than RON92, and can you use RON92 to save on fuel costs? Let’s have a discussion. What petrol do you use regularly, and why do you like your choice of petrol? Or are they all the same to you?

RON97, RON92, who is this RON person?

You might have seen numbers like RON97 and RON92 at your neighborhood petrol station. Fuel with a RON97 rating is more expensive, RM1.92 per litre at time of writing with the lower RON92 rating going for RM1.88. Have you ever wondered what they mean? Why is RON97 more expensive than RON92, and can you use RON92 to save on fuel costs?

RON stands for Research Octane Number, a rating used to measure a fuels knocking resistance in spark-ignition internal combustion engines. Before we attempt to understand this mumbo-jumbo, we have to know what knocking is. Knocking is what happens when parts or all of the air-fuel mixture prematurely ignites before the flame from the spark plug can reach it. This can be caused by ignition timing that is too early or engine overheating, where the heat from the cylinder itself causes the mixture to combust before the spark plug can burn the mixture. This causes a decrease in performance and might also harm the engine.

It is a misunderstanding to think that RON97 fuels produce more power than RON92 fuels, even more so with the fact that in reality a higher RON number means the fuel burns less easily! RON refers to the ability of the fuel to resist knocking and nothing else.

By pumping the RON97 into a car which engine only requires the RON92, all you’re going to get is an emptier wallet – that hardly counts for performance gains via weight reduction! :P

Engines are designed to have a minimum RON rating for its fuel. Do check your service manual for the minimum RON rating that it requires. For engines that require a minimum of RON92, you might as well pump RON92 fuel and save abit of money since RON92 is cheaper by 4 cents per litre. Another common minimum RON rating is RON95, but since we do not have RON95 fuel in our market, we have to use RON97 fuel for the engine. These engines normally have higher compression ratios, like the one found in the Satria GTI so it needs higher knock resistance to withstand higher compression.

If you find that your engine can use RON92 petrol and decide to save abit of money, do check out if a petrol stations RON92 petrol is leaded or unleaded. All RON97 petrol is unleaded, but some RON92 petrol might be leaded although this is very very rare. Buy me a teh tarik with the money you save, thanks! :)