I have an 02' EX sedan and the dealership recommends using 87 octane in it. Why is this and will it hurt to run 92 or 93 oct.?

 

Running higher octane gas will only barely increase gas mileage/performance on a stock civ, and when I say barely, i mean BARELY. The higher octane helps prevent preignition, or knocking, on engines with higher compression ratios, or boosted engines. There is really no reason to run it on a stock civ unless you really want to spend the extra couple dollars on the gas.

 

If the engine is heavily modded however, will a higher octane make a very noticeable difference in mileage/performance?

 

turbo/supercharged, yea. I/H/E no.

 

Thanks for the info. My car is N/A with a few mods so I don't need it then.

 

your more then welcome to pay the extra $ to put higher oct. in ur car, but by no means will it damage it. i hope that the honda dealership wasnt giving you that inpression.