This is my first and probably my last post with a tale of woe. Bought a - 2013 Mazda 6 2.2 Diesel sport, 80,000 miles, 1 owner, full service history, for £9,500 from a reputable car supermarket. Fantastic looking car with great leather interior and plenty of power. On day 3 of my ownership I took it to 60 mph on a country road intending to give it a bit more. At 60 mph the yellow engine light came on and a message "engine check required" so I backed off to 40 and continued my journey. The car sounded and drove normal. When I next started my car the light was out, but I decided to report the matter to the dealership. They did a test and said it needed a new oil pressure sensor so it was booked in for a few days later. They said it was ok to drive. The day before it was due to go in I was doing 40 mph and the red light came on with a message "stop, low oil pressure, check oil level, potential engine damage". I stopped, checked the oil and it was on the normal full level mark (not the x). I started the car and it sounded normal with no message showing so I drove at 1000 rpm the last short part of my journey home (hoping it was a sensor problem). Mazda dealers examined the car and said it needed injectors replacing, sump removing and the oil pump and strainer checking. When the sump was removed the engine was found to be damaged beyond economical repair (even though it drove and sounded normal).
Fortunately for me the dealers gave me a full refund and couldn't have been nicer about it.
I have read many forums and there seems to be more reports of oil contamination due to injector seals failing and oil pump strainers becoming blocked and there for starving the engine of oil. Along with DPF issues and having to reset various engine lights after an oil service I have steered clear of this Mazda engine and now own a newer Insignia with a lot more spec and manufacturers warranty. I sleep a lot better at night. Good luck everyone with your 2.2 engines (even if they are fully serviced).