I agree you won't damage the engine or any other part of the car by using 87 octane once in a while. If the recomended gas is 91 or higher then that is what you should use to get the most power the engine can produce. Todays cars can adjust ignition timing and such to compensate for lower octane fuel but don't produce their potential power on less than the recommended octane in most cases.on another note it seems to me that the dealer service you recived was horrible and you should at least inform them of that and maybe tell them if you recive similar service in the future you will take your business elsewhere. (just what I would probably do, but then again I like to bitch lol) hope your luck with the Z improves and good luck with it :thumbup:♣Zen31ZR♣ said:Hmm factory recommended 91 octane, as I recall. 87 might cause detonation to set in, and if the ECU could pull enough timing to stop it, then you'd end up with a lot less Hp.....If not, then you'd end up with engine damage. I generally would not recommend using less than the factory recommended octane.