If you are getting the drive to clean messages, it means that regens are not being completed. The filter is full and the pressure sensors in the DPF see that. A lot of city stop and go driving is not good for the DPF. If you know you are in a regen and have arrived at your destination, place the truck in park and let it idle for 30 sec to a minute. That will turn off the regen so you don't have the injectors dripping fuel which will get into your oil and further dilute it.
A digital monitor is very useful so you can see the status of the DPF and once you establish the average of when your truck goes into a REGEN (miles apart; mine is usually out at about 500 miles because I have a mix of city and highway in a 18 mile trip to work), you can keep driving and allow the regen to complete. You can also see your fuel level, DEF level, EGTs, etc.
If you don't want to buy a monitor, there are phone apps like Torque Pro and FORScan. You just need a Bluetooth adaptor for your OBD2 port to read the PIDS on your phone.
You can also have the 3rd screen, a ghost screen, on the gauge function onscreen turned on to see soot load percentage than you'll know when it goes to 100%, you will have a REGEN.