What oil weight is in the pan at this moment?
manuelga said:O/C oil as mentioned above,
& also sparks, sorry but I hate those Bosch (so my GA16'ed Sentra), get any matching NGK, if you want get the platinum ones from courtesynissan, for the SR20 (they work great in any GA16), I don't know if any temperature rate will be need to check for so colder weather.
Have you checked grounds & clean+tightened (+) connections at alternator & starter?
Check correct & also tightened relays & fuses under the hood.
Anything can create a false connection specially at those weather.
Also if you can, get an electric engine warmer.
Have you tried jumping battery from a running engine? maybe those will give you the extra ampers your GA is needing.