This is my first winter with anything but 15w40 dino rotella in the engine....I am now a Mobil 1 5w40 turbodiesel synthetic user. Coldest it's been so far up here is 22F one morning, glowed for about 7 seconds, cranked over 1 time and it was running smoothly, pretty awesome. I can tell that the oil lets it crank over quicker, it sounds a lot less strained. Same goes for our '83...it has the 0w40 mobil 1 in it, and it cranks right up in the cold temps. Plus I have 5 new glow plugs as of the middle of August....I had one die so I opted to just change all of them Couple that with my extended glow relay (keeps them on for 3 mins once its running) and it runs smooooooth.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)