Should I warm my vehicle up in cold weather?
Warming up a vehicle before driving it in cold weather has been a topic of debate for a long time. There are both advantages and disadvantages to this. The determining factors have also changed a bit with modern vehicle designs. Let’s explore this topic and see what the correct answer is for your situation.
The first question we should ask is, what is considered cold weather? For the sake of this discussion, we will call cold weather anything below 32°F or freezing. Very cold will be any temperature in the single digits or below.
Properly maintained vehicles with multi-port or direct fuel injection systems start much better in cold and very cold conditions. As the temperature decreases, the fuel does not mix with the air as efficiently. Fuel injectors are better at getting fuel to atomize (mix) with the air than carbureted systems. Carbureted vehicles require a much longer warm-up period in cold weather due to this fact. They are also much more prone to flooding and do not start well in very cold weather. Fuel injected vehicles have engine computers that use the information from several different sensors to determine the ideal amount of fuel to inject into the engine for optimum starting at varied ambient temperatures. They run better overall and can readily adapt to changing conditions.
Letting a vehicle run before driving in cold weather is a balance. With good and bad consequences on both sides of the equation. Knowing the facts can help you make the best choice for your situation.
The advantages of warming up a vehicle before driving
- Component lubrication. Warm fluid flows better than cold fluid. The use of synthetic fluids has improved cold weather flow but there is still a benefit to warming the fluid up before operation. Vital engine components require proper lubrication to prevent self-destruction.
- Prevents pressure spikes. Hydraulic systems, like power steering and automatic transmissions, require fluid flow to work properly. Cold fluid resists flow. Excessively cold power steering and transmission fluids forced to operate in cold conditions can lead to hose ruptures and system leaks due to high operating pressures.
- Driver comfort and safety.
The disadvantages of warming up a vehicle before driving
- Fuel consumption. Idling the engine to warm up the vehicle consumes fuel. Reducing your MPG (Miles per gallon), which increases operating costs.
- Moisture build-up. Think of a cold drink in a glass and the condensation on the outside. As the vehicle warms up, moisture builds up on the cold metal surfaces. The vehicle needs to be driven at operating temperature for several miles to burn off or evaporate the moisture. Excessive idling and short trips compound the moisture issue and can lead to a build-up in vehicle fluids and exhaust systems, which causes damage and reduces the service life of fluids. Your vehicle will require more frequent oil changes and fluid services to protect vital components.
- Time and inconvenience. Warming a vehicle up takes time. The vehicle needs to be outside and started ahead of time. If your vehicle has a remote start system and you park outside, this may not be as much of a factor.
- Increased emissions. Idling your vehicle produces exhaust emissions. When the vehicle is cold it produces more of the less desirable exhaust emissions. The faster we can get the vehicle to operating temperature and driving, the better it is for the environment.
As previously stated, it is a balance between the good and the bad. Each vehicle is different, and you need to adapt your starting procedure accordingly. Is it gas or diesel? Carbureted or fuel injected? Let’s start with some general recommendations and build from there. I would consider all these recommendations minimum warm up times while balancing increased fuel consumption. You can certainly let them warm up longer for driver comfort, but the increased fuel consumption will be noticeable between fill ups.
Cold weather (Below freezing)
Ideally, you will want to drive your vehicle until it reaches operating temperature. Then continue driving at highway speeds for several miles to remove built up moisture. If your commute is mostly within city limits, then plan a longer trip, at higher speeds weekly to remove moisture.
- Gas fuel injected vehicles. Start and let them run 1-2 minutes before driving.
- Gas, carbureted vehicles. Start and let them run 5 minutes before driving.
- Diesel vehicles. Start and let them run 5 minutes before driving. Diesel engines ignite the fuel with heat and compression. Additional warm-up time aids smoother engine operation. Be sure to run winterized fuel when the temperatures are below freezing. Remember to switch over fuels early or get additives in the fuel before it gets cold, so it has time to circulate through the system.
Very cold weather (Single digit temperatures or below)
Same recommendations as above but with more warm-up time figured in. The colder the ambient temperature gets, the longer the warm-up time needs to be.
- Gas fuel injected vehicles. Start and let them run 2-5 minutes before driving.
- Gas, carbureted vehicles. Start and let them run 10 minutes before driving.
- Diesel vehicles. Start and let them run 10 minutes before driving.
Additional cold weather recommendations
- Watch your engine temperature gauge. When the needle starts to move up, the vehicle is ready to be driven.
- Until your vehicle reaches operating temperature, TAKE IT EASY! I can’t stress this enough. Accelerate, turn, and brake smoothly and slowly.
- Set interior heat to defrost with low-speed fan until the engine temperature reaches at least 150°F. It may feel cold at first but, this allows the engine to reach operating temperature faster.
- Battery cranking amp capacity is reduced during cold temperatures. If you live in an environment that sees temperatures below freezing, have your battery condition checked annually. Installing a battery maintainer for use in very cold weather or if your vehicle sits for extended periods of time can be beneficial.
- Modern, properly maintained, fuel injected vehicles should not need block heaters or engine heaters to start in very cold weather. Diesel engines, on the other hand, will benefit from the use of block heaters during cold and very cold weather.
- Remember, excessive idling and short trips accumulate moisture in the fluids. Drive the vehicle weekly at highway speeds for several miles to evaporate accumulated moisture.
- Finally, if you park in a heated garage overnight you are the winner and don’t need to worry about any of this.
If you search the internet on this subject, you will find information that contradicts this article. Most of the industry is solely focused on fuel consumption and exhaust emissions. What we are discussing here is a balance between fuel consumption and what is best for your vehicle and driver safety. Most of us would consider increased fuel consumption as a fair trade for less breakdown repairs and our family’s safety.
Hopefully these recommendations steer you in the right direction. Remember, these are generalizations that need to be adapted to your specific make and model. A 2.0 Liter 4-cylinder engine will warm faster than an 8.1 L V-8 engine with rear heat. Warm up times will vary. See what allows you to drive the vehicle, without straining the systems, while efficiently reaching engine operating temperature. If you are unsure what is best for your vehicle, stop in and see the experts at Sanderson Auto Repair.
Aaron B.