I was driving my 63 plate 6 diesel on the motorway when I felt it pulling (accelerating) once or twice. A little later I changed gear and the revs spun all the way round to max as I dipped the clutch. Both events were not normal, of course, but without thinking clearly about it I put it down to the engine doing the 'clean the DPF' routine. (With hindsight, I know it would never do that when clearing the DPF.)
Some time later, the 'low oil pressure' warning message appeared, and I pulled off the A road onto parking very soon. I checked the dipstick, and there was no sign of oil there, and no oil on the ground below the engine. I put in the litre I was carrying, but still none showed on the dipstick. When the recovery man turned up we put in another 4 litres - that put it on the dipstick! So, by the time I stopped there was either no, or virtually no, oil left in the engine.
As the car was still under warranty, and after investigation by a Mazda dealer, Mazda UK agreed to replace the turbocharger at no charge, but were not paying for any further investigation or replacement of other parts.
I felt that any engine that has run without oil is liable to fail catastrophically at some point in the future, and so did not want the car back. Eventually I came to an arrangement with the supplying dealer who is in Oldham [far from me] to buy it back, though he would not pay me more than £1000 less than the trade would expect me to pay for one of the same age and mileage. I was forced to accept this deal, as I could not prove that the failed turbo had caused the loss of oil, or that there was subsequent damage to the engine (although I personally have no doubt that both are true).
Having subsequently driven my new replacement with the same engine, I am aware there was a noise from the previous car that should not have been there, which I think was the turbo, as it came and went sort-of_but_not_exactly with the engine revs. (I did wonder if Mazda had added a noise on purpose to 'make it sound better' , at the time. The noise was not high-pitched, like the whine you hear from some turbos.)
So if you drive a diesel-engined model, and hear a noise related to the engine, but not the engine, or see smoke from your exhaust, start worrying!
If you feel the engine pull or rev without you using the throttle, I recommend you pull over immediately, and switch off!!
What has really pissed me off, is that Mazda UK would not help make up the difference if I bought second- hand (from the dealer who supplied the car), and only contributed a paltry £500 to the purchase of a brand new car from my local dealer.
The car in question is a dark blue SEL NAV Tourer, with about 50,000 on the clock, and the bag-hanger hook on the offside of the boot is missing. It had the registration Lima Tango 63 Lima Juliet Alpha - the last time I saw it.
Beware.