97 or 95 Octane Petrol for My Car?
With today’s high petrol prices, every increase even if it is small can affect your monthly running cost and this is more critical if you drive around more often than others. Petrol companies usually offer various blends of petrol with octane levels ranging from 95 to 97 and even designer types such as the Shell V-Power. With the pricing of petrol for 95 and 98 differing by about 90 cents a litre, every full tank you fill up with 95 petrol can save you from RM39.60 depending on the size of your petrol tank (Perodua Viva fuel tank capacity 36 litres). By pumping 95 petrol instead of 97 petrol, if you save an average of RM39.60 per tank and you need to fill up 4 times a month, it works out to RM158.4 per month and RM1900 per year. But, is it necessary to use 97 petrol on your family saloon?
Petrol companies are offering various blends of octane levels to cater to customer demands. Some models with high performance engines, higher compression engines as well as turbocharged engines boosted to higher than factory levels need higher octane petrol in order to stave off engine detonation, knocking or pinking. Engine detonation occurs when the air/fuel mixture burns in an uncontrolled manner. Small uncontrolled explosions in the combustion chamber can gradually cause small dents in the piston and cylinder head that will eventually lead to a complete fracture. Some detonation can be heard especially when you move off from a standstill in second gear. It is the prolonged detonation that will cause the damage to the engine that most drivers fear. While the octane level of petrol can cause engine detonation, other factors such as high engine compression, advanced ignition timing map, too rich or too lean air/fuel mixture, air intake temperature and higher turbo/ supercharger boost pressure can influence its occurrence.
The octane number of a petrol measures its anti-knock quality or resistance to detonation. A 97 octane petrol is more resistant to knocking than 95 petrol. Petrol octane level is measured in RON Research Octane Number and is determined by testing it in a standardized laboratory multi-compression single cylinder engine.
Most car manufacturers specify the minimum petrol octane requirement for their cars and usually factor some safety leeway in their engines. This means that even if a batch of petrol falls to 94 or 93 RON, it will not affect the lifespan of the engine. Generally, most cars and even some turbo or supercharged cars can live with 95 octane petrol. As many of the cars sold in are automatic ones, the slower take-up of the automatic transmission puts less load on the engine and staves off engine detonation. In cars with manual transmission, unless you accelerate very hard, running on 95 RON petrol is very, very safe. Generally, most normal saloons will not benefit from running higher octane petrol unless the EFI Electronic Fuel Injection system has been reprogrammed to make full use of it through advanced ignition timing.
Drivers wanting to try out 95 RON petrol should check the car owner’s manual for the recommended RON requirement and if testing for fuel consumption, fill up your tank at least three times before making a judgment as the fuel injection system of an engine needs some time to readjust itself to the petrol. To determine your fuel consumption accurately, use your trip meter and divide the distance traveled with the number of litres filled up than you will get km/litre. Never use the fuel tank level as a guide as this can be very inaccurate.
In conclusion, most drivers can save money every month just by filling up with 95 RON petrol without affecting the lifespan of your engine. If drivers still insists on 97 RON petrol even if they don’t really need it, oil companies are not going to complain if you want to spend more money at the pumps. Well for myself, I am saving money every month on my manual turbocharged by pumping 95 RON petrol even though I am heavy footed on the throttle.
Credit to Auto Consultants
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