Conventional oil has a lower viscosity in a warmer weather, as it gets colder it get thicker lowering your RPM on start-ups, until the friction warms the rings, and the RPM’s start to climb into the range it needs to start.

Mercury motors need a high RPM before the injectors will fire. I would change over to full synthetic oil, it helped with my motor on P4 in the winter time. My 2 cents.

I put in at Colvill on 3-17 the north ramp ice free, and south is still iced up. Fishing very slow got 2 walleye 1 whitey.