Your Engine in Winter
Cold mornings are hard on engines and batteries. Understanding what the cold actually does helps you prevent the most common winter breakdowns.
Auto · Originally published November 16, 2016 · Updated November 2026
Southwest Missouri doesn't get the deep, lasting cold of the northern states, but a sudden drop into the teens after a mild week can catch a car off guard. Here's what cold weather does under the hood, and what you can do about it.
Your battery works harder in the cold
Cold slows the chemical reaction inside a battery, so it delivers less power right when a cold engine needs more to turn over. That's why a battery that seemed fine in the fall can quit on the first frigid morning.
- Have the battery tested before winter. Many auto parts stores do it for free.
- Clean any corrosion off the terminals and make sure the cables are tight.
- If the engine cranks slowly, don't wait for it to fail completely.
- Keep jumper cables or a portable jump starter in the car.
Oil thickens when it's cold
Cold oil flows more slowly, which means it takes longer to reach engine parts at startup.
- Use the oil viscosity listed in your owner's manual. Many newer cars call for thinner oils that flow better in the cold.
- Stay on top of oil changes. Old, dirty oil doesn't protect as well.
- Synthetic oil generally flows better at low temperatures. Ask your mechanic whether it makes sense for your vehicle.
Coolant protects against freezing
Coolant, or antifreeze, keeps the liquid in your engine from freezing and cracking parts. Water alone can freeze and do serious damage.
- Check the coolant level when the engine is cold. Never open a hot radiator cap.
- Have a shop test the freeze protection, and use the type of coolant your manufacturer specifies.
- Look for leaks, cracked hoses and worn belts, since cold makes rubber parts brittle.
How long should you warm up the car?
Many drivers grew up idling cars for 10 or 15 minutes. Modern fuel-injected engines generally don't need that. Most warm up faster by being driven gently after a short wait to let the oil circulate. Check your owner's manual for your vehicle's recommendation.
A few cautions:
- Never warm up a car in a closed garage, even with the door partly open. Carbon monoxide builds up quickly.
- Don't leave a running car unattended in the driveway or a parking lot. It's an easy target for theft.
- Clear all your windows before you go, not just a small patch.
Fuel and diesel tips
- Keep your tank at least half full in winter. It gives you a reserve if you're stuck in a highway backup and helps limit moisture in the tank.
- If you drive a diesel truck, diesel fuel can gel in very cold temperatures. Use winter-blend fuel when it's available and ask your mechanic about an anti-gel additive before a hard freeze.
What insurance does and doesn't cover
- Mechanical breakdowns and wear, such as a dead battery, a cracked engine block from the wrong coolant mix or a failed water pump, generally aren't covered by auto insurance. Some companies sell separate mechanical breakdown coverage.
- Roadside assistance, an optional add-on on many policies, can help pay for jump starts and towing when your car won't start.
- Theft of a car left running is generally covered under comprehensive if you carry it, though you'd still owe your deductible.
- Damage from a crash caused by a breakdown on the highway is generally covered under collision for your car and liability for others.
Not sure what you carry? Our guide to what "full coverage" means explains it, and the auto coverage checkup makes it easy to review. For ways to save without giving up important coverage, see how to lower your car insurance.
Talk to a local agent
Want to add roadside assistance before the cold sets in? Call 417.865.4800 or learn more about auto insurance from our local team.
Common questions
Does car insurance pay for a dead battery?
No, a dead battery is a maintenance issue. If you carry roadside assistance, it may help pay for a jump start or tow.
Is it bad to idle my car for a long time in winter?
Most modern engines don't need a long warm-up and warm faster by being driven gently. Long idling also wastes fuel and leaves the car vulnerable to theft if you walk away.
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Written by Auto Insurance Express. Reviewed by Philip Edwards, founder. Philip has run independent insurance agencies in southwest Missouri since 1997. More about the agency.
General information, not advice about your specific policy. Coverage, exclusions and eligibility are determined by the policy forms and endorsements your insurer issues, and state rules change. Confirm details with us before you rely on them.
