Your best bet is to stick with Mobile 1, its been proven to be very effective and stays clean longer. I tried ZMAX and wasted my money. My 97 explorer had cloged fuel injectors and after using ZMAX it still had the same problem after a week, then I decided to go to a garage and have the injectors cleaned, runs alright now. didnt notice any increase in gas millage or power, but the K&N air filter did a make difference. I just use Mobile 1 10w-30 oil and a bottle of chevron fuel injector cleaner once every 3 months.