Originally Posted by jobrien
I didn't say that all gases did not have detergents. I said running a higher octane tank through once in a while would help clean. I said this because a higher octane fuel burns more efficiently thus more of the fuel is burned in the chamber and this CAN help keep it clean.
Using higher octanes CAN cause your car to run more efficient too because more of the gas is burned/ignited in the chamber so more of the fuel is being burned instead of going out your tail pipe, which means potentially better gas milage too.
When the engine is fully warmed up, there shouldn't be any undetonated fuel exiting the tailpipe. If there is, something else is going wrong. I don't know where you got the idea that higher octane fuel burns more completely than lower octane fuel, but it isn't true.