the higher the octane rating, the harder it is to ignite, so you usually step you spark plugs up one or two "temperature" ratings... the reason you'd upgrade is so that the gas ignites all at once, and doesn't detonate early. you only need that on high compressions, or turbo'd vehicles from what i understand (thats why our cars need 93... i think)
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Greg
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96 Black SVX LSi beater
90 Red Eclipse GSX track ho
99 Ford F250 work horse
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