Hi Tachymeter,
I too live in a cold country, where cold starts are known to be the main enemy of the engine internals, taking miles off engine life every time you fire up. There are a few P6's around Norway still, and I've never heard of any not dealing as well with the cold as other cars. In fact, the rear suspension gives the P6 superior traction (!) compared to other RWDs.
The most common winter advice is to definitely use an engine block heater if you have one (I wish I did), change to 'winter' grade motor oil for better viscosity, and maybe a beefier battery that has been tested for cold weather performance. Appropriate anti-freeze mix ratios apply, usually 30-40 pct. With a good battery (mine is 65 amps I believe) safely in place I run the starter for a few seconds before pulling the choke, so that the 1500-2000 rpm full-choke idle doesn't come with clatter. I've not done so myself but with all the adjustability of the P6 in virtually *every* department I would take the fast-idle down a notch on the choke mechanism if you feel it a bit high.
As far as chrisyork's mention of water in the fuel tank, old cars tend to suffer some from condensation forming in the fuel supply pipes/carburettors during warm-up. I add condensation remover (200 ml to a tank) which helps keep my high-mileage V8 sharp in the morning. I think you can also find radiator 'capes' to help speed warm-up, they were fashionable in the 1960s and '70s. Good luck for the season!
