If your car won't start in the cold, the best solution combines proper maintenance and options to make a cold start easier on your vehicle. In northern Wisconsin, cold winter weather is a fact of life. My 2007 Saturn Ion starts in weather as cold as -25°F actual temp without fail, without any special treatment. (But not everyone is so lucky.) We have a fleet of trucks at work (both diesel and gas) that run in all kinds of weather. I’m drawing on my experience working with them, and from full time mechanics that help troubleshoot when we need them.
If Your Car Won't Start in Cold Weather, First Check for Proper Maintenance
- Make sure you have the right oil. Most cars now recommend 5W-20 for year round use, or synthetic such as Mobil One.
- Have your battery checked. In our area, most auto parts stores will do this testing for free. Car batteries can fail after 3 or 4 years, a quick test will tell you if you have a weak battery and it needs to be replaced. You can also test your alternator to see if it is charging the battery properly.
- Get service if it is needed. If you have a check engine light on but don’t notice any change in performance, there may still be a problem with your ignition system that will get worse in cold weather. Electronic ignition on modern vehicles is more dependable than ever, but coil packs do fail. There may also be other problems that only a mechanic with the right diagnostic equipment can troubleshoot.
Side note – when you take your car to a service station for oil change, don’t let them fill your washer fluid reservoir. They typically use a low grade washer fluid that will freeze when the cold comes. Once that happens you will be at nature’s mercy until it warms enough to pump it out. Get cold weather windshield washer fluid.
When Winter Hits – Steps to Improve Cold Weather Starts
There are several things you can install to warm the key parts to make cold starts easier. It's better to get the installation done before cold weather hits, but options like an engine blanket can be easily added during cold weather. Note: Cars and trucks built after 1990 have fuel injection. The recommended starting sequence should be in your owner’s manual.
Use a Battery Blanket
A battery blanket is a straightforward way to avoid some cold start issues. Cold weather slows the chemical reaction inside your battery that makes the electricity to turn the starter, and can rob you of 30% of your cold cranking power. A battery blanket needs to be active for about an hour to do its job and warm the battery to the core. Get a battery blanket on Amazon.
Try an Engine Block Heater
Engine block heaters come in 3 different types:
- Magnets that attach to the oil or transmission pan
- Block heaters that are installed in the cooling system
- Frost plug heaters
You can install these yourself if you do some research and make sure you have the right style for your particular application. (I would get a mechanic for the frost plug style) When doing research to write this post, I found that Amazon had a built in guide to help you find the right one for your engine. Just type in the make, model and year to find the right fit.
No matter what style of engine block heater you have, an hour should be enough to warm the engine once it is plugged in. There are timers you can purchase that can be set for an hour before you need to start your car that will save you money. Because they create heat, all of these heaters draw quite a bit of current and should be plugged into a 20amp breaker that does not have other appliances.
Start Your Car the Right Way
The way you start your car can improve your chances of a cold start.
- First, turn off the headlights and blower for the heater.
- Next, turn the key to the on position and wait until the dash lights quit flashing. This allows the fuel pump to pump additional fuel in for the cold start.
- Finally, turn the ignition key and crank the engine for up to 10 seconds. If it fails to start, wait 30 seconds and try again. Don't try this more than 3 or 4 times. At that point you likely have a dead battery and you will need to find a way to recharge it.
To jump start your car or other vehicle – pay attention to the color codes on the jumper cables and battery terminals. Make sure the red goes to the positive post and the black negative ground is attached to the engine block. Allow several minutes for the battery to recharge (with the jumper car running) before you try to start your vehicle. It takes 12 minutes or more for a working alternator to recharge a cold battery, so don't shut off the car after it is jumped until it has been driven an adequate amount of time.
Cold Weather Start with Diesel Engines
Diesel engines have glow plugs with an indicator light that tells you when they have warmed enough to attempt a start. Diesel engines start harder because of higher compression and a higher flash point for the fuel. For temps below zero, we always plug our trucks in to warm the engine block.
HEET™ Fuel Additive – Yes or No?
Modern fuel contains an ethanol mix of 10% or more, so you shouldn't need to treat your fuel with “HEET™” gas line anti freeze. (Assuming you use your car regularly.) If you have a diesel engine, you should use a fuel conditioner at the recommended rate. It is also beneficial to keep your tank past half full to minimize condensation in your fuel tank. Water lowers the octane of the fuel and causes poor performance. Additives such as Sea Foam motor treatment can boost octane and remove water for better overall performance.
My Car Still Won't Start – Now What?
This is an introduction to cold weather car starts, not a complete guide. Always refer to your vehicle's owner’s manual and back that up with the advice of a reputable mechanic. Modern auto mobiles often stay on the road for 200,000 miles and are complex in design. Sometimes even the professions have problems troubleshooting issues.
Don't Forget to Check Your Tires
Don't forget to check the air pressure in you tires. Rich says, “I started my Ford Edge today and took it for a ride to just drive it and charge the battery. It was pulling to the driver's side so I checked the air pressure and it was less then 10#, when it should have 35#. I checked all 4 and the MOST I had in any tire was only 25#. I know cold weather drops the air pressure because I always have to inflate my wheel barrow. This is something we don't want to do when it is cold, but really should.”
You may also find our other Common Sense Preparedness posts useful, including:
- Winter Car Kit and Winter Vehicle Maintenance Checklist
- 4 Layers of Cold Weather Clothing That Everyone Should Know
- Emergency Heat During a Power Outage and other Winter Storm Preps
- Protecting Plant from Frost – 12 Ways to Beat the Cold Weather
- Roadside Emergency Kit Recommendations and Checklist
This post is by Laurie Neverman's brother, Richard Poplawski. Since his service in the Marines, Rich has been a mechanic, fabricator and “fix just about anything” guy for over 20 years. He lives in northwest Wisconsin in the farmhouse that was owned by his grandparents, and maintains a large orchard and perennial plantings, as well as a vegetable garden. He loves spending time with his grandkids, introducing them to gardening or getting in some fishing with “Papa Rich”.
His posts on the site include:
- How to Grow the Best Raspberries You've Ever Tasted
- Growing Blueberries – Quick Guide and Master Grower's Tips
- 5 Things You Need to Know Before You Buy a Wood Burning Stove
Originally published in 2016, updated in 2018.
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