The petrol that we find at petrol pumps these days are mostly RON97, with RON92 being available at a few stations (I can only think of Shell stations that have previously been Projet stations, Esso and Mobil stations). RON92 is the cheapest petrol at RM1.88 per litre. There are two different grades of RON97 available – the usual is priced RM1.92 and there is only one premium brand – Shell V-Power Racing, priced at RM2.15.
The government is proposing that these grades of petrol be revised to RON95 and RON99 instead. RON95 will be subsidised and have its price kept low, while the subsidies for RON99 fuel will be much lower, although still subsidised. This would mean the gap of price between the two grades of fuel will be much larger than compared to the current RM1.88 versus RM1.92 for RON92 versus RON97.
By doing this, the government thinks it effectively takes some burden off the low to middle-class income earners while the rich who “drive SUVs and performance cars” can pay more for their RON99 fuel, which will give them “better performance.”
In reality I can only think of a few cars that would require a fuel with an octane running higher than our maximum of RON97 to achieve its peak horsepower – the Honda Civic Type R and the Volkswagen Golf GTI which both run optimally on RON98 fuel. The engine’s computer automatically retards ignition timing to compensate for lower octane fuel – this means you won’t be getting the spec-sheet horsepower figures you paid for.
Some engines do more than just retard ignition timing. The Mazdaspeed 6 which needs at least RON91 (RON93 for optimum horsepower and torque) for example, cuts off its 2.3 litre DISI turbocharged engine’s boost through the means of a wastegate from 4,200rpm onwards to protect the engine.
The thing is, while filling up your car’s fuel tank with fuel that has a lower octane rating than specified will decrease performance, or with some old engines even damage the engine, unless you modify your engine like advance your ignition timing or run higher boost for example, you’re not going to get any benefits by using a fuel with a higher octane than required like RON99 fuel, unless the fuel companies are going to skimp on the additive package with the lower octane fuel, which is most likely going to be the case if the new RON95 is going to be offered at a lower price than our current RON97 price of RM1.92.
Saying RON99 fuel will offer better performance than RON92 based on octane alone is completely wrong, and plenty of luxury cars these days these days only require between RON92 and RON95 fuel, though it will work with fuel as low as RON91. Some latest generation normally aspirated Mazda engines have an even lower octane requirement, working perfectly fine and in fact designed for RON87!
But I must say that RON95 is a sweet spot choice, as alot of engines that are considered to require what is called “premium unleaded fuel” world-wide these days usually mean it needs a minimum of RON95.
As always, check with your workshop or manual to find out what octane your engine needs. Proton’s Campro engines and most of the 16 valve Mitsubishi engines installed in Protons (4G92 in Wira 1.6 and 4G93 in Satria GTi) run on a minimum of RON95. Buy higher octane fuel only if you like what the particular fuel’s additives package gives your engine and think the benefits are worth it. This can be very different from car to car, and alot of it depends on feeling, so its a very personal thing.
UPDATE #2: Many of the low to middle income consumers in Malaysia keep their cars for as long as 10 to 15 years or more. Old engines may and most likely have combustion chambers that are loaded with carbon deposits, affecting its shape and creating hot spots around. This increases the chances for engine knocking by a margin despite the proper fuel octane used. So for old engines, sometimes higher octane fuels have to be used to prevent engine knocking which will result in engine damage. Thus RON97 in a RON95 engine… I guess this is what we have been doing all this while.
UPDATE: DPM Najib Tun Razak says the government will decide on its plan to slash the subsidy for the higher grade of petrol before the end of 2008.
How much do you think the new RON95 and RON99 fuels should be priced at? And which would you choose to fill up your tank with? As additional reading, find out more about fuel octane from the links below.