How to start a car in cold weather

A cold winter morning is one of the worst times to have trouble starting a car. Unfortunately, those same cold mornings are also times when you are most likely to have problems. If you live in a cold area like Baltimore, Salt Lake City, or Pittsburgh, here are some tips to help you start your car on a cold day and help you avoid car problems in the first place.

To know what to do to prevent cold weather starting problems, it's helpful to understand exactly why cold weather makes it difficult for cars to start. There are four reasons, three of which are common to most cars and the fourth to older models:

Reason 1: Batteries hate the cold

Cold weather and car batteries just don't mix well. Every chemical battery, including the one in your car, produces less current (mostly electricity) in cold weather, and sometimes much less.

Reason 2: Engine oil doesn’t like cold much either

In cold weather, engine oil becomes thicker and does not flow well, making it harder to move engine parts through it. This means that your battery, which has been weakened by the cold, actually has to do more to get the engine moving so it can start.

Reason 3: Cold weather can cause fuel problems

If there is water in the fuel lines (shouldn't be, but it happens), sub-zero temperatures can cause the water to freeze, blocking the fuel supply. This is most common in fuel lines, which are thin and easily clogged with ice. A car with frozen fuel lines may roll over normally, but it will not drive on its own.

Be warned by diesel drivers: Diesel fuel can "thicken" in cold weather, which means it flows more slowly due to the cold, making it difficult to get it into the engine at start-up.

Reason 4: Older cars can have carburetor issues

Cars built before the mid-1980s usually used carburetors to mix small amounts of fuel with the air in the engine. Carburetors are very delicate instruments that often don’t work well in the cold, particularly because tiny nozzles called jets get clogged with ice or because fuel didn’t evaporate well in them. This problem doesn’t affect cars that don’t have carburetors, so if yours was built in the last 20 years you don’t need to worry about this. However, drivers of older or classic cars will need to be mindful that cold weather can cause carburetor issues.

Method 1 of 4: Prevent Cold Weather Starting Problems

The best way to deal with cold weather starting problems is to not have them in the first place, so here are some ways you can prevent them:

Step 1: Keep your car warm

If batteries and engine oil don't like the cold, keeping them warm is the easiest, though not always the most practical, approach. Some possible solutions: Park in a garage. A heated garage is great, but even in an unheated garage your car will be warmer than if it were parked outside.

If you don't have a garage, parking under or next to something large can help. Park under a carport, a tree, or next to a building. The reason lies in the physics of heating and cooling, and a car parked overnight in an open shed or under a large tree may be a few degrees warmer the next morning than one parked outside.

Use a battery heater or cylinder block heater. In very cold climates, it is common, and sometimes necessary, to keep the car's engine block warm overnight. This is achieved with an engine block heater that plugs into an electrical outlet to maintain a high temperature, helping oil and other fluids flow faster (this is especially important on diesels). If this option is not available, you can try a plug-in electric heater for your battery.

Step 2: Use the right oil

Consult your owner's manual for information on which type of oil to use in cold conditions. Modern synthetic oils run pretty well in the cold if you use the right oil. You will need to use a multi-purpose oil marked with two numbers (eg 10W-40 which is common). The first digit with a W is for winter; lower means it flows more easily. There are 5W- and even 0W- oils, but see the manual. It is even more important if your car uses regular oil, not synthetic oil.

Step 3: Avoid Fuel Problems

Auto parts stores and gas stations sell dry gasoline for gasoline cars and fuel conditioner for diesels, both of which help fight fuel line freezing and, in the case of diesel cars, gel formation. Consider running a bottle of dry gas or conditioner with every tank of diesel from time to time. Note, however, that your fuel may come with these additives directly from the pump, so check with your gas station before adding anything else to the fuel tank.

Method 2 of 4: Getting Started

But how do you actually start the car? A simple turn of the key, as usual, can help, but in very cold weather it's better to be a little more careful.

Step 1. Turn off all electrical accessories.. This means headlights, heater, defroster and so on. The battery must be fully charged to turn on the engine, so turning off all electrical accessories allows for maximum amperage.

Step 2: Turn the key and let it spin a little. If the engine seizes immediately, great. If it doesn't, crank it for a few more seconds, but then stop - the starter can easily overheat if it runs for more than ten seconds.

Step 3: Wait a minute or two and try again.. The situation may loosen up a little, so don't give up on the first try. But don't try again right away: it may take a minute or two for your battery to be able to perform at full capacity again.

Step 4: If you have a carbureted car (meaning one older than 20 years), you can try starter fluid. It comes in an aerosol can and is sprayed into an air cleaner - let them show you how to use it at an auto parts store. Depending on starting fluid isn't great, but it can work in a pinch.

Method 3 of 4: If the engine turns over slowly

If the engine starts but sounds slower than usual, warming up the battery may be the solution. Unfortunately, this usually requires you to uninstall it, so if you don't know how to do that, skip to the section on starting the migration.

Another thing to check if you have the tools and know-how is the battery cables and clamps. Corroded clamps or cracked cables can block the flow of electricity, and right now you want everything you can get. If you see corrosion, clean it with a wire brush; cracked cables must be replaced. Note that if you've never done this before, it's best to see a qualified mechanic.

Method 4 of 4: If you need a jump start

Necessary materials

• Another car that drives well
• Another driver
• Eye protection
• Battery cable kit

If the engine does not turn at all or turns weakly, and you have already tried everything, you need a start from an external source. Here's how to do it safely:

Step 1: Put on your goggles. Battery acid accidents are rare, but when they do happen, they can be serious.

Step 2: Get Good Cables. Purchase a good (not worn or cracked) set of battery cables.

Step 3: Park close. Position your "donor" car (one that starts and runs normally) close enough for all cables to reach.

Step 4: Start the Donor Vehicle. Start the donor vehicle and keep it running throughout the process.

Step 5 Connect Cables Carefully

• The positive (red) on the car that won’t start. Connect it right to the positive battery terminal or bare metal on the clamp.

• Next, put the positive on the donor car, again on the terminal or clamp.

• Ground or negative (usually black wire, although sometimes white) on the donor machine, as above.

• Finally, connect the ground wire to the stalled car - not to the battery terminal! Instead, attach it to bare metal on the engine block or bare bolt attached to it. This is to prevent the battery from exploding, which is possible if the circuit is not grounded.

Step 6: Check your connection. Get into the "dead" car and check the electrical connection by turning the key to the "on" (not "start") position. Lights on the dashboard should light up. If this is not the case, move the clamps a little to get a better connection; you can turn on the headlights to see how you get on with it while you work under the hood (bright light means the connection is good).

Step 7: Start the Donor Machine. Run the donor car for a couple of minutes with the engine running at about 2000 rpm, doing nothing else. You may need to increase the engine RPM above idle to accomplish this.

Step 8: Start the dead machine. Now, when the donor car is still running at 2000 rpm (this requires a second person), we start the dead car.

Step 9: Leave the dead machine running. When the machine that has stalled is running smoothly, leave it running while you unplug the cables in the reverse order from above.

Step 10: Leave the machine on for at least 20 minutes.: This is important: your battery is not charged yet! Make sure the car has been running for at least 20 minutes or driven 5 miles (the more the better) before shutting it down or you'll have the same problem again.

A warning: It’s important to understand that cold doesn’t just temporarily disable batteries, it can also permanently damage them, so if you’ve needed a jump start once you should get your battery’s health checked as soon as possible.

Good luck out there — and drive carefully in the snow!