Cold weather use K20A3 oil choice

0W-30. But to get for Chicago winters, block off part of your radiator. I lived there for a year and it was brutal getting the engine warm to go home from work (garage at the house).
To cross the country in the blizzard of 66 I dumped out a cardboard box of clothes in the trunk and blocked the radiator with the cardboard. Only way to get heat into the cabin and onto the windshield.