>There are three grades of gas here. It is based on Octane. Regular, a blend of regular and premiun and Premium. The higher the octane, the 'better' the gas is for the engine. eg. less carbon and it ignites better fewer emissions.

My understanding is that higher octane doesn't make the gas any better. It's just a matter of what the engine has been tuned for. That is, if your owner's manual says to use regular, you should. Premium only if the manual calls for it.

Tamar