I took the Grey Ghost (99 Buick Park Avenue 110,000 mi) in for an oil change and the mechanic said the injectors were "a little dirty". So, two questions- What is the diagnostic tool? And is this worth $65? In the past I have put a can of Techron fuel injector cleaner into a full tank and ran the car for 200 miles or so at freeway speed and this seems to work, as the car has a smooth idle and very good gas mileage after the treatment. What say you all?