My car, a Mazda 6 TS2 Diesel 2.2, is kept in the Alps during the winter at a height of 1300 meters. In February for two weeks, the temperatures ranged between -19c and -10c. The first part of any journey is four miles downhill.

Consequently, if the ambient temperature is -17c, the wind chill effect would make the engine even colder as we go downhill. Three times it failed, as I got to the bottom of the valley, and to the first upward incline.

The symptoms were always the same. The engine lost power, would idle smoothly but would kangaroo if driven on the flat but would stall on an upward incline. There were no warning lights at any time and Mazda’s computer diagnostics showed nothing.

FIRST FAILURE:
The fuel tank had mostly winter diesel in it (75% winter and 25% non winterised). Temperature was -18. Car was abandoned. I returned to it later when it got a little warmed (ie, about -11c). As the tank was nearly empty, I filled it with winter diesel, it worked perfectly.

SECOND FAILURE:
Four days later it failed again at -17c. A garage cleaned the whole fuel system and put an additive in the fuel tank. It then worked perfectly.

THIRD FAILURE:
Three days later it failed again at about -17c. A Mazda main dealer said that it might be frozen crystals in the turbo or injectors. They said that they put the car in a warm room and it then worked fine. They also put an injector cleaner additive in the fuel.

After recovering it from the garage the temperatures returned to normal (about -10c at worst). It's worked perfectly since.

Mazda UK have no answer to this despite being requested to contact their European counterparts. Mazda’s breakdown insurance paid all costs associated with recovering the car and getting me to airports. They also paid half the fuel system cleaning invoice.

I’m really worried that it will happen again this winter if we get extreme conditions. What do you think is happening and can I take any precautions (Other than making sure that I have winter diesel in the tank)?