I am in Lansing, MI right now and it is also only 7 Degrees, I am gonna head out and do some errands...I bet my SD will start right up for me. (it does reliably without a heater as low as -10F) Two years ago it started at that temp with 15w40 dino oil in the sump...truly amazing. Now that it has 5w40 Mobil 1 its pretty much effortless.

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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)