Smart Or Stupid - Can You Mix RON95, RON97, RON100 Fuels?

Can you mix RON95, RON97 and RON100 fuel in your car?

For the uninitiated choosing between the yellow and green or sometimes red nozzles can be a little confusing.

Of course, to those of us who have had even the briefest talking-to about the matter will recognise that it is, in fact, quite trivial. Mostly, the colours correspond to the price we have to pay, but it also relates to the different RON value assigned to the fuel.

Before we continue, it’s worth explaining what - not who - exactly is RON. As you’d expect, it’s an acronym, and it stands for Research Octane Number. It’s the most common form of octane rating and is used worldwide and is determined by the fuel’s ability to resist knock or premature combustion when under high pressure.

As we know, the internal combustion engine generates power by an explosion that results from an air and fuel mixture that is compressed by a piston, and should only ignite in a controlled manner by a spark plug at the apex of that piston’s arc to ensure maximum energy release.

The more pressure that fuel mix can handle without self-igniting is denoted in the RON number designated to it and is determined by a number of factors under strict testing lab regimens.

Knock Knock

This phenomena is something you may have already heard of and results from an engine that experiences isolated premature ignition of its air/fuel mixture under normal operation, though there are many other reasons it happens in day-to-day driving.

It typically occurs as a result of the incorrect use of grade petrol, and while it is damaging to the car if left neglected, it isn’t the end of the world. Engines suffering from excessive knock can still be driven, but the driver will notice a sluggishness, lack of power, and some excess noise.

Petrol companies and car manufacturers work hand in hand to ensure that knock is avoided, of course. Modern vehicles have sophisticated monitoring measures to regulate the fuel mixture and detect knock before it can reveal itself via those aforementioned outward symptoms.

Even if knock is detected, the ECU (Engine Control Unit) can make adjustments to prevent its manifestation such as, among other things, reducing the potency of the air-fuel mixture via the injectors, retard or speed up the spark ignition - all without the knowledge of the driver.

That all said, every modern petrol-powered car in Malaysia is rated, certified, and optimised to run on RON95 fuel to the point that you paying extra for RON97 or above is just a waste of your hard-earned money as your engine will need to work harder to adjust to the higher RON fuel suited for higher compression engines.

More Power?

With the RON values forming a tier of differently priced fuels, oil and gas companies will naturally try to justify the higher cost of their RON97 or higher performance petrol. In addition to the higher resistance to knocking and the ability to sustain higher in-cylinder compression, these fuels also have a more robust additive package, or so the companies advertise.

V-Power, Blaze 100, or Primax Pro-Race all speak of a higher concentration of additives mixed in with the fuel. Everything from friction modifiers to improve fuel economy and performance, to corrosion inhibitors, to more exotic and chemically complex ones that improve engine response and prove some topical cleaning abilities to the fuel system and valve-train and even to reducing the build-up of internal carbon deposits.

In the long run, you could argue that this higher quality (and more densely packed) additives are worth paying the extra over the base RON95 as they could help prolong the health and service life of your engine. Then again, there are no independent testing results to definitively prove this to be the case.

With regard to any additional performance benefits attributed to the mere RON value of a fuel, it really depends on the car you’re driving and the engine it is running. Apart from any anecdotal or experiential opinion someone may have formed, fuelling up with a RON97 fuel (or higher) won’t turn your Myvi AV into a high performance machine.

The higher RON value merely allows an engine tuned for higher compression to extract the most power it already is able to generate without suffering premature ignition or ‘knock’. It just so happens that these engines are generally fitted into higher performance cars, so we get the impression that they could be beneficial to our daily driversHowever it’s’s important to remembr, that those higher performance cars might need fuel with a higher RON value to run properly and smoothly.

If your car runs smoothly on RON95, and especially if it is rated for it (check your fuel filler cap to confirm), there is no huge benefit to changing your habits. Any improvement in response and smoothness you might feel after filling up with, for example, Shell V-Power could be totally attributable to the placebo effect.

And let’s not forget the more robust additive packages included in those more expensive fuels. You most likely are feeling those effects instead of the higher RON value.

You’ll Always Have A Mix

If your fuelling habits are similar to most Malaysians, you aren’t tied to a single brand of fuel. Even if you are, you might reach for the RON95 nozzle most of the time and perhaps occasionally the one for RON97.

Assuming you don’t bleed your fuel system or pull up to the petrol station on a bone dry tank (definitely not recommended) before your next refill, you’ll always have some blend of RON95 and RON97 (or higher) sloshing around in your tank.

You’ll never have 100% RON95 or RON97 or the same blend from the same company. Yet your car, along with everyone else’s, still seem to work just fine after pulling away from the pumps.

Again, modern petrol-powered cars have sophisticated systems built in to adjust the combustion process for the fuel that is being fed into them so you don’t have to worry. If you’re getting your fill at a reputable petrol station that gets its high quality fuel from another reputable oil and gas company (and unless you’ve pumped in diesel by mistake), you car WILL NOT EXPLODE.

Conclusion

On a personal note, it’s quite amusing to find people still asking about the possible benefits and pitfalls of mixing and matching different RON95 with RON97 (or higher) fuels from different fuel providers.

Ignoring the health hazards of sugary beverages, it’s like mixing and matching different brands of sodas together, yet we never question that line of thinking.

Can you mix Coca Cola with Pepsi, or Mountain Dew with Sprite despite them coming in different bottles, have differently coloured bottle caps, and are made by different fizzy water companies? Of course you can.

The resulting concoction might taste awful, but you’ll still function. Thankfully cars don’t have taste buds like we do.




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