If 6/7000 I would change them only refill oil to 1/8 inch below full mark as per Mazda instructions use Mazda oil only use high grade diesel try motorway run keeping revs 3000 plus should start a regen and keep it going then rely on regular oil changes check oil level by the stick each week. 6) Clean or Replace DPF. If a clogged, damaged, or blocked DPF is the cause of your problem, you will either have to clean it or replace it. If it isn't damaged, start cleaning the system first. When it comes to cleaning the DPF, it is generally recommended to take the car in and look for special assistance while attempting to clean the DPF. smES2.