I just thought of one more thing.

Did you use a genuine Volvo oil filter? Some aftermarket oil filters have problems:

1) some don't have a proper checkvalve -- this keeps oil in the filter from draining out between running periods, and results in starting the engine with an empty filter, so pressurizing the oil channels of the engine block is delayed.

2) I've also heard that certain filters (I can't remember the brand, since I didn't bother noting it -- I only used Volvo brand) cause a problem in pressure (maybe poor filter material) that results in such erratic idiot light flickering. I think the post said that he suffered such problems until he changed his filter.

Of course, any such problem will be exacerbated in very cold weather. I hope these possibilities help you.

Regards, and happy holidays.