what grade gas do you all use in your civics? i just put some 91 octane gas in my GFs civic, and she got all pissed at me and said it was too high octane, that she 's only supposed to use regular 87 octane gas. is there any reason not to use a higher octane gas?

 

I use 87 because its cheap.

 

It's more expensive.......

 

The octane rating of gas refers to the percentage of octance (C8H18 I believe) in the gasoline mixture. 87 octane gas contains 87% octane, 89 contains 89%, etc. The rest of the gasoline mixture usually contains heptane (C7H16 I believe). Octane gas can be compressed quite a bit before it spontaneously ignites (engine knocking), but heptane gas spontaneously ignites very easily when compressed. So, the higher your compression ratio is, the higher octane gas you should get to prevent prevent preignition. For example, my Mini Cooper S has a supercharger, so I cannot get gas with an octane rating of lower than 91.

 

i just use 87 octance 1) because its cheap 2) thats what the manual says to put in it 3) it runs fine on 87 regular

 

I use midgrade in my civic and premium in my S15 (for obvious reasons). There is actually a noticeable difference between regular and midgrade in terms of gas mileage and pickup. Just personal preference. But yeah, when it's $1.97 a gallon for regular, it can be a little steep to use higher grade gas.

 

tomuch octane can burn ur heads and cause other damage on ur car in a civic u should use 87

 

Not on a built engine.... and midgrade is fine for any Civic, stock or otherwise

 

octane is a buffer to burning. so really, there is no way that too high will burn the heads. unless you try throwing in some methanol or nitromethane. pump gas wont hurt your car. its just a waste unless you need it. in an FI engine or a high compression engine, you need the higher octane to ward off detonation. and theres no way im putting 87 in my civ

 

100 all the way for me. Ok, 87...