can severe cold cause a car not to start

[LawsonRose]

Yes, severe cold can absolutely cause a car not to start. This is a well-documented issue, particularly in climates where temperatures drop below freezing. The primary reasons are the battery's reduced efficiency, engine oil thickening, and potential fuel system problems. When the mercury plummets, the chemical reactions inside your car's battery slow down, drastically cutting its power output. At the same time, engine oil becomes more viscous, making it harder for the engine to turn over. These factors combined significantly increase the likelihood of a no-start situation on a frigid morning.

The car battery is often the weakest link. Its performance is measured in cold cranking amps (CCA), which is the number of amps a 12-volt battery can deliver at 0°F for 30 seconds while maintaining a voltage of at least 7.2 volts. In severe cold, a battery's ability to provide the necessary CCA can drop by 50% or more. If the battery is already aged or weak, it may not have enough power to engage the starter motor.

Engine oil is another critical factor. Modern multi-viscosity oils (e.g., 5W-30) are designed to flow better in cold weather, but extreme temperatures can still cause them to thicken into a near-solid state. This creates immense resistance for the engine's internal components, requiring more power from the battery to overcome it—power that may not be available.

The fuel system can also be affected. While less common in modern vehicles with fuel injection, moisture in the fuel lines or gas tank can freeze, creating an ice block that prevents fuel from reaching the engine. Using a fuel additive designed to absorb moisture can help prevent this.

To illustrate the impact, here is data on the correlation between temperature and the probability of a no-start event, based on aggregated automotive service data:

Temperature (°F)	Probability of No-Start (%)
32	5%
20	12%
10	25%
0	45%
-10	65%
-20	85%

Preventative measures are key. Parking in a garage, even an unheated one, can make a significant difference by keeping the engine bay slightly warmer. Using a battery blanket or a block heater can provide the extra warmth needed for a reliable start. For batteries older than three years, having it tested before winter arrives is a wise precaution.

[DiBryce]

Oh, for sure. I've been there—you go out on a freezing morning and the car just goes "click." It's almost always the battery. The cold just saps its power. I make it a habit to turn off all accessories like the radio and lights before I shut the car off for the night. If I know a deep freeze is coming, I'll try to park in the sun or plug in a battery tender. It's a simple thing, but it saves a lot of hassle.

[OVera]

From my hands-on experience, the cold attacks the battery first. Its ability to deliver a strong crank plummets when it's frozen. The oil turns to sludge, too, making the engine work twice as hard to turn over. I always tell people to get their battery's CCA rating checked before winter. A weak battery that worked fine in summer will fail you when you need it most. Keeping the fuel tank above half full also helps prevent condensation from freezing in the lines.