Spark plugs.
Are you replacing some? Is your customer? If you’re trying to solve a misfire problem, STOP!
You might want to take a look at the original plugs to make sure you’re replacing them for the right reasons. Most original equipment spark plugs have a life of more than 100,000 miles thanks to electrodes that contain precious metals like platinum and iridium. If the plugs fail sooner than the recommended interval, you need to solve the problem before installing new plugs. Some auto manufacturers have issued Technical Service Bulletins concerning excessive oil consumption.
Learn more from my latest installment of Counter Intelligence.