Reducing PLA Jams
1) Set temperature at 205C. Now, there could be a lower temperature at the nozzle, but the additional 15C above PLA rated temperature leaves a lot of room for preventing a cold jam.
2) First tried setting the PID_MAX to 150, got jams. Set it to 200, got wildly varying temperature around setpoint. Set to 175 and go a reasonable response. Your mileage can vary, but PID_MAX value will contribute in a better sense that PID autotune.
3) Use sunflower oil to season the stainless steel heat sink. Used a syringe and needle to drop a few drops of oil into the heat break before every print, then let 10cm of PLA just flush the excess oil. I cannot believe how less a force is required to extruder 1.75 mm filament through a 0.4mm nozzle, after what I have dealt with in the recent past.
4) aligned the filament straight into and out of the extruder motor.
Result. A 6 hour long print, no jams, completely unattended during this time.