Mitsubishi Engines - RON92 vs. RON97

The "knocking" noise comes from ignition happening too early in the cycle, and is usually an indication of using a fuel with too low a RON rating.

What does the car's manual say on the subject of correct fuel type?

PW - not familiar with "RON" reference - would this be the same as our "Octane" (alkane) over here?

Yes, it is. RON is an abbreviation for Research Octane Number.

http://en.wikipedia.org/wiki/Octane_rating

Thanks PW - y'all always want to be different.....I also noticed a new fashion trend @ Wimbledon........

Any gas under compression is heated. The compression in an engine heats the air fuel mixture. If it gets too hot you will have fuel igniting before the spark plug fires. This throws off the engine timing. The pinging and knocking is from stresses on the engine of firing when its not suppose to. The higher the octane rating the more compression need to get the fuel to self ignite.

The manufacture design the car knows what the compression is of the engine and has given his recommendation in the car manual. Read it

This may not be correct if modifications have been made after market to improve performance the engine.

Assuming that your engine is tuned to factory specifications you could:

1. Retard the timing slightly, till it quits pinging (slight loss of power)

2. blend the two fuels in some ratio when you fill the tank. You'll need to experiment with the proportions of the two grades of petrol to find the least expensive mix that doesn't make the engine ping.

Good luck

As already mentioned, but to my mind not given enough "weight". Pinking (as it is called) WILL damage your engine......

So either adjust the timing to use the lower RON gas, or just use the higher one....

In retrospect, I would get the ignitionj timing also checked for accuracy, and correct functionality of the advance & retard mechanism.....