Yes, cold weather can absolutely stop a car from starting. It's one of the most common causes of winter breakdowns. The primary culprits are your car's battery and engine oil. A chemical reaction inside the battery creates power, and cold slows this reaction down significantly, reducing its cranking amps—the power available to turn the engine. At the same time, engine oil thickens in low temperatures, making the engine harder to turn over. If the weakened battery can't overcome the thickened oil, the engine will crank slowly or not at all.
How Cold Affects Key Components:
- Battery Performance: A fully charged lead-acid battery has about 100% of its power at 80°F (27°C). This drops dramatically as temperatures fall.
- Engine Oil Viscosity: Multi-viscosity oil (e.g., 5W-30) is designed to flow better in cold weather than single-grade oil, but extreme cold still increases its resistance.
| Temperature (°F) | Relative Battery Power (%) | Engine Cranking Speed (%) |
|---|
| 80°F | 100% | 100% |
| 32°F | 65% | 85% |
| 0°F | 40% | 65% |
| -20°F | 20% | 40% |
Beyond the battery and oil, other factors contribute. Fuel delivery can be an issue if moisture has frozen in the fuel lines. Diesel engines face an additional challenge with fuel gelling, where paraffin wax in diesel fuel solidifies, blocking filters and lines. Using a block heater or parking in a garage can mitigate these effects by keeping the engine bay warmer. If your car doesn't start, the first step is always to try a jump-start, which points directly to a depleted battery.
