In cooler climates multigrades have the advantage over mono's for the very reason you have mentioned.
Multigrades are less viscous at lower temperatures than monos, so offer less resistance to cranking (easier faster starting) and better cold engine circulation.
Cold weather also reduces the speed of chemical reaction, that generates electrical power, in your battery, for your starting circuit.
Winter is when most marginal battery's show their age.
A poorly performing battery will eventually damage your starter motor -$$$$
The prudent owner will change the battery as soon as its deteriorating performance has been confirmed. I go for one overnight charge - the battery will usually give good performance straight after the charge. If on the way out, show diminished cranking ability on subsequent starts - REPLACE.