Kubota's using DEF on the bigger ones, I want to say 80hp+. I suspect that it'll work it's way down to the smaller ones in time, though. Nightmare on tractors to put DEF on them, as it has a shelf life-that is dependent on temperature and humidity. Tractors sit. If the DEF sensor senses that the DEF isn't good quality, it derates the tractor and you basically get to idle and that's about it. Or if a operator fills the DEF tank with diesel by mistake, it can be upward of $20k to fix it all...crazy expensive! So be careful....
You are correct. They will regen, but after so many regen's the ash builds up and then the filter needs to come off and be professionally cleaned. Currently for the small DPF's, we're looking at about $400 locally. The only one we've had to do was a 3301 where the operator ignored the beeper, lights, and lack of power, and plugged the DPF. It has soot level "stages" 1 through 5, with 4 and 5 derating the engine power severely to the point where it will barely make any power. On the 3301, it makes about 15hp at stage 4 and 5. Stage 4 MIGHT (or might not) do a forced regen through kubota's software, and 5 needs the DPF removed and either replaced or cleaned professionally. What I don't like is that as the engine wears, oil usage will go up. Oil gets into the DPF and plugs it faster, so regen cycle times will get more frequent. Only heard of it one one occasion. That owner rolled the tractor over and then righted it, then attempted to start it. Bent one rod and it has low compression-which puts unburned fuel and oil into the DPF.
They put a beeper on it for a reason. They also programmed derating for a reason. Operating with a plugged DPF creates crazy high EGT's which can melt pistons, so they did this stuff to protect the motor and the operator.
