Most of the DPF flashing light issues relate to oil-dilution, caused by the post-combustion diesel injection, used to regenerate the DPF. Why Subaru couldn’t have spent the few extra dollars for a dedicated DPF fuel injection system, to avoid the oil-dilution issue, I’ll never know.
It’s an excellent engine with good driving characteristics, completely let down by a rubbish DPF management system.
Excellent resource: subdiesel.wordpress.com/ecu-analysis/dpf-management/
Basically, driving short trips increases soot generation and the DPF requires more frequent cleaning (oil-dilution). A regen on the highway ~100 km/h will raise oil-dilution by 0.2 to 0.3%. If you drive on the highway for 100 to 200 km, the dilution will reduce by about 0.2%. So, if you drive between say Mackay and Rockhampton every day this is the car for you. You most likely won’t ever have an oil-dilution problem, and you’ll get to the 12500 kms between services.
If, however, you get stuck in increasing traffic or at lights when the DPF management system decides to do a regen, it is relentless. It will continue until it is complete, even if it has to stop and start the regen process a couple of times – even if the car is turned off it will try to regen again once the car is started and back up to temperature and speed. In this case I have seen oil-dilution increase by OVER 2%. Do this a couple of times and you are up to 10% oil dilution which means an oil change. I’ve had an oil change at less than 2000 km because of consecutive short trips.
