I went 355,000 miles on my original injectors. I had the truck in to a Cummins repair shop, to fix an oil leak, while it was in, I decided to bite the bullet and replace all the injectors, as preventative maintenance. Of course I will always wonder how long they could have gone, if I didn't replace them. I do change the fuel filter (always fleetguard), every oil change. I also run Valvoline injector cleaner about every 10k.