I hope all of you are using gas cleaner at least once a month ? I use 1 bottle to a half a tank of gas every 3 weeks . At 116,000 miles , I have to say it is working and with ORIGINAL spark-plugs !!! I use wallmart super tech gas cleaner that is in a white bottle . Also use GAS DRYER once a month in the winter . LONG live the zetec !!! I will take a zetec over a 2.5 anyday.