Hey guys, got a stupid question for ya. What octane fuel should I use in CO, we have 85, 87, and 91. I used 85 for the first tank, and didn't hear any knock, but I'm not sure I would have heard it. Is that too low for this motor? I got 29.5 MPG, but I've had a heavy right foot since I just got the car, still pushing it to see what I got. anyway, your thoughts? I tried searching, but didn't find the answer. Thanks.

 

try running it on 91 and see what mpg you are getting
you would know if it was knocking, you would hear it - what type of car do you have?

 

that's what I was thinking, try a few tanks on each grade on see what happens. I thought I would hear it knocking if it was, but it's so new to me I don't really know what to expect, and what sounds are normal for this car and which ones aren't. It's a 2000 civic Si, so it's got a b16, is that about right for mileage?

thanks

 

thought that such info is given in the owners manual.
just follow that - some cars have that info printed inside the gas door.
dont remember if honda does or not.

 

Both of my Si's run happily on the regular gas, not sure about your year, though.
You will not hear the knocking, because your ECU will adjust the timimg to dumpen it. So, if you do not have the manual and cannot find one, you can just compare the milage, as it was mentioned above.

 

no manual, didn't come with one.

thanks