PETALING JAYA: With the fuel price dropping, more drivers are filling their petrol tank with RON97 due to the longstanding belief that it is able to give them more mileage and better engine performance. Another reason that for the switch is the fact that the price difference between RON95 and RON97 is getting less significant than before. Currently, the price for RON95 is RM1.70 per litre while RON97 is RM2 per litre which is merely a 30 sen difference as compared to previously the price difference was RM1. In a survey done by theSun, many perceived that filling RON97 for their vehicles have improved their vehicle engine performance as well as providing them with more mileage in long distance travel. RON stands for Research Octane Number, a number that is awarded to different grades of fuel with regards to its capability to resist auto-ignition or engine knocking. The higher the octane number the more the fuel can withstand compression before it detonates. Hence, is RON97 really better than RON95 in term of better mileage and engine performance? According to writer Kelvin Ang from carreviewsncare.com, using RON97 for your vehicle does not necessarily gives you more mileage or better engine performance because the amount of mileage you will get depends on the traffic conditions, the way the driver drives and what type of vehicles they drive. "Every driver has the chance to achieve good mileage with their vehicles, if they do it the right way. "If you are one of those drivers that has a passive driving personality most likely you will be able to obtain greater distances with your vehicle," he said. He added that using a higher grade RON fuel such as RON97 in your ride simply means that your engine will find it more difficult to auto-ignite or also known as knocking as the resistance is now higher. "However, if your car does not require RON97 fuel, it is best that you stick to RON95 fuel as there are no proven statistics that prove that RON97 fuel performs better than RON95 fuel for a vehicle that carries on the same engine as otherwise it could ruin the car engine in the long-run or even result in an explosion," he said. Echoing with Ang's statement, former automotive magazine editor Douglas Tan said that if your car engine is optimized to run on RON95, filling it up with RON97 will give you no performance or efficiency gain. "At the most, you may notice smoother engine operation, but that would be thanks to the better grade of fuel that comes with a RON97 rating, and not because of the fact that it is RON97," said Tan when contacted recently. Tan added that this was proven through many tests conducted which indicated a drop in horsepower for the car as well as causing engine knocking that can result in some serious implications.