I have a 2018 Mazda CX-9 with 53,000 miles on it. I take my vehicle to the dealer for the 'free' oil changes every 7,500 miles. Starting back when the vehicle had 23,000 miles on it, the service department has been typing in "Recommend Fuel Injector Service" on every service ticket. Does anyone know what is included in this service, and whether or not it really needs to be done (and if so, at what intervals)?