Spud,
I'm across the pond from ya, temps are about the same even if we get more snow from the lake(Trade ya!).
I ain't an exspurt, but this is my annual sw fiddling regimen.
Husky sells a lighter winter blend Bar oil as does Stihl. Both work great down to zero, but I can't vouch for below that. When it gets below zero, I often have other projects in the Barn that seem to take priority.
When it starts getting cold(About now) you're gonna have to tweak the High and low settings anyhow, just set the high a smidge rich, and low just to the point the idle drops on the rich side.
When you start the saw, let it idle or hold it just above idle for a minuite or two for a couple minuites. Let it get warm, and let the clutch and chain get warmed without a load. Kinda like foreplay.
I havn't tried the cold weather kits yet, no need as far as I can tell.
If it gets too dadgum cold, out I'll pick a better day in the teens or warmer.
A big +1 on not over dressing and getting frothed up.
An underlayer of Polypropelene long skivvies, a carhart jacket, and Mil-surp ECWS bibs or pants is all I need to stay toasty when working in the cold.
Ya can't sit still long, but then it's an incentive to keep moving.
Eyepro can be a bit of a pain with fogging up, so pick a hat without a bill.
I hate it when the glasses fog, and then freeze up!
The vented Gargoyles look goofy(Buddy Holly gone 80's new wave) but do vent well, and the Oakley M-frame with a lens that is more open like "Sweeps" work well for me.
Am still looking for good winter gloves.
Holler if you find something that really works.
Good luck to ya, and mind that Manitou!
Dingeryote