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The numbers on the pump signify the RON or Research Octane Number of the fuel you’re loading. In the simplest sense, RON determines the fuel’s anti-knocking quality or its resistance to detonation. Though a car’s energy is made by the burning of the fuel, it must be done at a precise time. If not, you’ll notice a ‘knocking’, ‘rattling’ or ‘pinging’ sound. This means that the fuel has burned off or detonated before the optimal time. This equates to a waste of energy, and in the worst case, damage to your engine in the long run.
Fuels with higher octane numbers will eliminate knocking. You have to consult your owner’s manual as to your vehicle’s minimum RON octane requirement, a fact that’s especially true for high-end sports cars. However, it’s good practice to have older cars, designed to run on lower RON fuel, switch to higher octane gasoline to reduce the changes of pre-ignition brought about by built up contaminants and carbon deposits.
Each time you refuel, you’ve probably entertained the thought of switching either to a lower or higher octane fuel. Which one’s better? What should you be using and could you be using the wrong one? Here’s a basic rundown about available fuels at the gasoline station. They’ll go by different names, so in this case, it’s better to use a general terminology.
Regular Unleaded has a RON of 93. If you’re running a low mileage car, or a non-performance (i.e. small grocery getter, sub-compact hatchback) car, there’s no need to extend your wallet to anything else but this stuff. It will do the job just fine, especially if the manufacturer of your car recommends it. If your car requires a higher octane and you find yourself filling up on this stuff, you’ll find deteriorated engine performance and worse fuel mileage; sometimes offsetting your initial savings filling up.
Up one step and slightly more expensive on the gasoline ladder is Premium Unleaded which carries a RON number between 95 to 96. They have a higher tolerance to knock compared to Regular Unleaded and as such, will give your additional performance and a smoother engine because it’s running at its optimum. As mentioned earlier, if your car’s already knocking on Regular Unleaded, switching to Premium Unleaded will lead to a smoother driving experience, especially on older, higher mileage cars. Of course, if your manufacturer recommends using 95 octane, then stick to that.
The most expensive and the one with the highest octane would be Ultra Premium Unleaded, having RON figures 98 and above. This high octane fuel maximizes engine performance and tends to burn more cleanly thereby reducing pollution. For performance cars, especially those with turbochargers, this would be the norm. Normally though, if your car doesn’t require such high octane fuel, you will find little or no benefit from switching. Though some swear that they get better mileage or better power using the highest octane fuel, as long as you’re meeting the manufacturer’s recommended RON, you’re fine.
The RON numbers may generally mean nothing to the average motorist who usually cares more about getting the cheapest fuel out there. However, before letting your wallet decide, consider the requirements and condition of your vehicle. Though fuel mileage and performance still lies ultimately in the car’s state of tune and the driver, always remember what’s recommended by your manufacturer. If it says to load up on 93, then go for it. However, if it says you have to go 95 or 98, there’s no reason for you to go lower. You’ll surely regret it with noticeably less power and mileage; and potentially a damaged engine.