The octane number isn't a percentage. It's just a reference number assigned for comparison purposes to indicate a fuel's resistance to knock. Dealership personnel often give out incorrect information on fuels. I have heard them say it's okay to use 87 when a manual calls for 91 or 92, and also to tell owners to waste their money on high octane when the car doesn't need it.

Unless your car has a high performance engine in it and the owner's manual calls for 89 or 92 octane, then there is no benefit to using it. In a high performance engine, the compression ratio is high and the computer is set to use far advanced spark timing for maximum power. This makes the engine more likely to knock, and to resist that knock you need higher octane gas.

Engines today are equipped with knock sensors which will retard the timing to stop it if it occurs. So, in theory, using a lower octane fuel than the owner's manual calls for is not going to harm the engine if you only do it a few times; however, it will reduce performance and lower fuel economy, and may cause carbon buildup if done often. On the other hand, if the engine is set up for regular 87 octane, it will not have the ability to advance the timing far enough to take advantage of 89 or 92, so using a higher octane fuel than the owner's manual calls for will not improve performance, economy, or engine life. All it will do is cost you money.

Some Acuras that I know of do call for 91 or 92 octane, but most Hondas probably call for regular 87. If that's what your manual calls for, there is no reason to buy 89 or 90.

you said it cowboy. if your car dont call for high octane gas, dont use it. unless you like throwing money away. well your not throwing it away really, i work in the petroleum industry, and those extra few cents you spend on premium gas will help pay for some of my perks. so yes go ahead and buy it. hahahahaha