Yesterday Morning it was 4 degrees here in Buffalo. My procedure for the 1983 3oosd is to Double Glow then depress the pedal 1/2 way once and turn the key. Started right up. I do use Mobil 1. Prior to this my car had sat for a week.

I feel glowing twice is important because you have to overcome the effects of moisture in the combustion chamber. More pronounced in cars that don't have everything just right or have less than optimal compression. Cars parked outside seem to have more of a problem starting then those that are garaged.

Prior to my current ownership I have owned a 1975 240D and a 1979 300D. Both these cars would start ok down to abt 20 degrees. So I used a block heater plugged into a timer and determined they would both start up great after abt 2 hours. The big plus here was almost instant heat.

Good luck - art