by sunrisemac » Thu Aug 28, 2014 10:57 pm
A bit of info I found amongst my junk for reference
<<Unleaded fuels carry a RON (Research Octane Number) rating. Put simply, RON determines petrol's 'anti-knock' quality or resistance to pre-ignition; or if you want to put in another way, the Octane Number denotes its resistance to detonation.
If you run your vehicle on low octane petrol you might notice a 'knocking', 'rattling', or 'pinging' sound (as it’s often called), which means the fuel is detonating instead of burning smoothly. This is not only a waste of energy, but it can also damage your engine in the long run. Burning is the desired effect of any internal combustion engine (not an explosion per se).
Fuel with a higher octane number suitable for your vehicle's engine will eliminate knocking. Older cars that were designed to run on a lower RON fuel can also benefit from a higher RON, because the older the car and the higher the kilometres, means the engine will have a greater propensity to knock. This is mainly caused by a build-up of contaminants and carbon deposits which, when hot, can cause pre-ignition.>>