Starting a cold-soaked engine (starting below 32F) progressively increases wear that could add hundreds of hours of wear to the cylinders. Below 20F, preheat is needed. The different metals in the engine contract differently at these low temps, leading to increased wear. Using Multi-Viscosity oils such as 20W50 we use in our aircraft, reduces cold weather wearing significantly. Remember, over priming can lead to a hazardous condition that can cause an engine fire. Under priming will cause the engine to not start. Some experimentation is required. Don't run the starter more than 10 seconds without a 30 second pause. Properly primed, it should start quickly.