you can use the lowest RON or octane rating available as long as your engine wont ping or will have detonation. in my local NA cars i use 93 octane with no problem, and on my japan domestic cars (surplus cars) i use 95 because japanese engines have higher compressions than the local counterparts. and in my turbocharged gasoline engine, i only use 95 or petron blaze, if i use 95 RON, my car idles bad and has problems on boost. and in my pickup i have been using jetti for awhile already because of their 2 pesos discount and it is the most convenient station from my place, but i will be switching to shell because i have just bought new diesel injector nozzles and many say that shell diesel is better than jetti. common misconception is that higher octane burns well and easily, and that higher octane will give better mileage or better power. maybe if you have a higher compression rating or depending on your timing settings. but with a factory tuned local engine with lower compression and conservative timing settings i think 93 will do just fine.