up until January end 2008 - i worked on mazda's in a Mazda Dealer. The company i worked for - i worked on Jaguar, MAZDA, Land Rover, Rover, Citroen, Mitsubishi & LDV. We sold all of these vehicles through our Franchise departments.
ALL DPF systems use diesel to operate !
However only Mercedes, Audi, BMW, Jaguar, Landrover use systems which do not require additive to be added to the system. They are over £30,000 to £80,000 plus per vehicle hence the DPF system is much more advanced and cuts service costs for the ownerd.
The DPF system on Citroen, and Mazda, use additive which needs to be replenished on demand. this varies depending on driver patterns.
Your MAZDA 6 Diesel DOES NEED additive. Check your hand book that came with the vehicle and all the information will be in there.