10 degress fairenhiet is cold even in canada. i have a 2002 jetta tdi and live in canada. at 10 F it will start but that is border line for starting. this car has the oil pan heater. it is a 4 inch square heating pad glued to the pan. less than one hour plugged in and voom voom.
i have a 2006 golf now also. it needs a heater. i bought the in line collant heater for this one. i seen that there is a in line heater made specifically for tdi's. i think it was on this site. it looked cool but hard to get here in Canada so i bought a universal one. bit more screwing around to install but way cheaper.