I know its shouldn't have knocked but it did (Very weird I thought). I drive 55-60K a year and have done so for the last 17 years with my job. What Ford writes is generic lawyer waffle car companies love putting into manuals. Plenty of tests have shown higher octane fuels delivers more kms per tanks. I will agree with you on oil supplement and additives, best thing to do is take a long drive if you want your car to operate at peak performance.

