My dealer never told me that I have to use a Octane 91 for my vehicle. It is just 1200 miles old and I have been using 87 so far.

Is it advisable to change to 91 at this point?

Does 91 give me more MPG than compared to 87?

 

Do a search, this topic is brought up several times a month. Always use premium as specified by the manual as you can potentially ruin your engine otherwise.

Did you not read the manual or look at the sticker by the fuel filler where it says "Always use premium unleaded fuel"?

We should make a "Always use premium octane like the manual says" sticky thread.

 

Use premium. The cars ecu is designed to run using premium octane fuel. Any high compression motor should be ran using the highest octance available at the pump. If you want to run 87, trade the car in and buy a civic.

 

Yepper.....couldn't agree more 91 octane is the Minmum octane. Mid grades around here _ NY Area - is 89 so that doesn't work.... I use premium always. If you are going to spend the extra $3 on a 10 gallon (30 cents difference per gallon for Premium) fill up, IMO, I want the most out of my car, as it was designed to do, particularly if you drive this car as the personal Sports sedan that it is !!

 

well, unfortunately both the times i filled up a tank, it was on a full service and never got a chance to see what was written in the fuel tank...

my dealer explained many dos and donts and seems to have missed this one...

i will certainly go for 91 going forward, but wanted to ensure using a 87 so far and changing to 91 would not screw things up

 

And with the rising cost of gas, it will be a difficult transition for you.

Not to mention for the rest of us, it will just keep hitting us.in the pocket!

 

You will be ok. The benefit of higher octane fuels is that octane is added to fuels during the production process because it allows the gas to burn at a slower rate, thus giving you a more complete combustion of all gas inside the cyclinder. This slower burn rate also leads to less carbon build up because there is more complete combustion of the gas. Lower octane fuels burn hotter and flash off much faster and this can lead to incomplete combustion. This in turn gives you worse gas mileage since you ecu is going to be demanding more fuel per mile to give you the same combustion performance as the higher octane fuel. The ecu is designed to provide a certain amount of spark, the crank is desgined to produce a certain amount of stroke and time between intake and exhaust so that all of the fuel is burned completely during combustion. The 87 is cheap, but you will get more gas mileage and the performance the motor was designed to make, making the cheaper gas more expensive in the long run.

 

Well said....Envied. as an additional note, mnay cars that operate with 87 Octane requirements, and despite much advise out there that higher Octance will do nothing for your car, I have found that every few other tankfuls, using 93 Octane on other cars: Mazda 3 and 2010 CRV, alttle better response and mileage, not a fantastic difference but I do notice it...so every 3 or more fillups I will use a 1/2 tankful of premium fuel on thos cars.

 

Thanks for saving me the trouble.

The ECU will correct for lower octane (i.e. if detonation occurs, it will pull the timing). You will not get the same performance but you will NEVER notice the difference.