Unless I am mistaken, the high bypass turbo fan engines in passenger jets don't use diesel engines and thus don't need to meet the diesel engine emission regulations. You will find that the on road regs are much tougher than the off road regs we have on the farm. Think those large container ships that sail past my house don't have emissions regs to meet? Think again. Same planes, they have to meet strict emission and noise regs too, never mind the mind boggling regulation that aviation has to adhere to .

Nobody says you have to like DEF, but some people really are exaggerating about how hard it is to use? Maybe it is on Deere and Case, but Agcos engines are pretty good now after initial issues (which they were very good about addressing). I still have more hydraulic leaks that DEF issues, by a long way.