The winter months often bring snow, ice, low temperatures, and a significantly altered morning routine. From unearthing the kids’ hats, gloves, and boots to clearing your driveway, cold weather can make for a stressful start to your day, but advances in automotive technology mean that there’s one common winter task you can cross off your list: warming up your car. While the process is ingrained in many drivers, it’s not really necessary for any vehicle produced within the last 30 years.
Why has the myth of prolonged warm-up persisted for so long? The practice is largely driven by tradition and received wisdom. It’s the same reason that many drivers still believe that premium gas offers improved performance in all vehicles and that oil needs to be changed every 3,000 miles, even though new engine and motor oil technology now puts that number closer to 5,000 to 7,500 miles. Generations of drivers grew up hearing the old “let the car warm up” rule, and treated the advice as gospel even as modern engineering rendered the guidance largely obsolete. There’s also a slight psychological factor at play here, as many drivers, regardless of the data, simply feel like they’re being more mindful owners by allowing for an extended warm-up period. Let’s explore some of the reasons why the warm-up period is so outdated, look at a few of the pros and cons, and give you a good excuse to spend a few extra minutes nursing your morning cup of coffee.
A New Era of Engine
Ultimately, there’s no simple yes or no answer to this question, and it all boils down to one key factor: age. While older vehicles can typically benefit from a prolonged warm-up period, this practice has become largely irrelevant for modern vehicles. Today’s fuel-injected engines are designed to deliver peak performance and efficiency right off the bat. While letting the vehicle run for 30 seconds certainly can’t hurt, a faster timeline is unlikely to result in a major breakdown or significantly compromised fuel economy. Drivers should try to avoid any extreme acceleration or high engine RPMs until the engine hits its normal operating temperature, but that doesn’t mean you need to spend 10 minutes killing time in your driveway while the needle creeps towards the halfway point.
The same can’t be said for older cars, which, due to their outdated technology, need a little extra time to get going on a cold winter morning. Before the advent of modern fuel injection technology, most vehicles relied on carburetors to supply the engine with a precise mixture of fuel and air. Found in many cars, trucks, and SUVs produced before the 1990s, carburetors were designed to operate at a specific temperature and relied on engine heat to achieve the correct air-fuel ratio. Failing to allow for a length warm-up period, typically anywhere between three and five minutes, could lead to an engine that was prone to stalling and running a little bit rough. However, the carburetor wasn’t the only reason that older vehicles needed a little extra time to get going.
Advancements in Oil Technology
There have also been significant advancements in motor oil technology over the last 30 years. Older, conventional motor oil was typically produced using mineral oil, which tends to be a lot thicker at lower temperatures. For this oil to flow effectively through the engine and penetrate hard-to-reach components, it required ample time to warm up and become less viscous.
Modern, synthetic motor oils are designed to be much more stable across a wider temperature range, which means they will begin to flow through the engine as soon as the engine is started, even when the thermometer dips below the freezing point. These synthetic oils also contain numerous additives, including anti-wear agents, detergents, and friction modifiers, which coat critical surfaces even after the engine is shut off and provide instant protection as soon as you turn on the ignition. The engines found in today’s vehicles are designed to work with this new generation of thinner, low-viscosity oils, which is just one reason why it’s so important to choose the right product when performing an oil change. Using the wrong oil, or trying to save a few bucks by sneaking conventional oil into an engine designed for synthetics, can result in everything from reduced fuel efficiency and overheating to more serious outcomes like premature wear and outright failure. That said, there aren’t any serious downsides to using synthetic oil in an engine designed for a conventional formula, aside from the added cost.
Pros and Cons of a Winter Warm-Up
There’s more to a car than its engine, however, and there can be some advantages to letting the engine run for a little while before setting off. Let’s look at some of these, as well as some reasons to keep your warm-up as short as possible.
Pros
Visibility: There’s not a great case to be made for warming up the engine from a mechanical or performance perspective, but safety is another matter altogether. The snow, ice, and frost that come with winter driving can turn the windshield into an opaque slab of impenetrable glass. While a good ice scraper and some elbow grease will usually do the trick, there are times when a little extra assistance is needed. Running the defroster for just a few minutes can enable drivers to cut through even the thickest ice or snow. A vehicle’s climate control system needs to draw heat from the engine to raise the temperature, so the engine must warm up before this is most effective. Addressing a frozen windshield isn’t just a good habit. It’s legally required in most areas, as it’s actually against the law to drive with an obstructed view.
Warming Up Fluids: As we discussed, modern synthetic engine oil has been specifically designed to provide near-instant lubrication, protecting vital and expensive engine components. Unfortunately, the same can’t be said for some other important fluids that you’ll find under the hood. Brake fluid, power steering fluid, and automatic transmission fluid can all benefit from a brief warm-up period, which reduces viscosity and allows them to perform as intended. Cold transmission fluid can lead to slow, hard shifts and increased wear and tear on one of your vehicle’s most expensive parts, while power steering fluid requires a little warmth to ensure the system operates with the correct hydraulic pressure.
Comfort: Finally, there’s the comfort factor. If you want to enjoy a cozy commute, allowing your vehicle to idle isn’t the worst idea in the world. In addition to making for a more pleasant driving experience, a warm cabin can also reduce the distractions that might come with shivering in your seat or hunching over to conserve warmth as you cruise down the road.
Cons
Fuel Waste/Emissions: The most compelling argument against a prolonged warm-up period comes down to a matter of cost. Even when a vehicle is idling, it still consumes anywhere between 0.2 and 0.5 gallons of fuel per hour, and that number can rise even higher when the climate control system is working hard to defrost the windshield and warm the cabin. That might not sound like much, but it can certainly add up if you’re routinely giving your vehicle a long warm-up session. There’s also the environmental aspect. Vehicles can still produce plenty of CO2 emissions even when they’re idling, and activating the air conditioning can add another 7% to 20% to their total carbon output.
Time: While some people have hammered out a solid morning routine, many of us spend the wee hours running around the house to quickly complete chores, choose an outfit, and grab a quick bite before we head out for a hard day’s work. Squeezing in an extra ten or even five minutes to warm up a vehicle can throw the whole schedule off and create a hectic start to your day, forcing you to willfully ignore the speed limit in order to make it to work on time.
Engine Wear: Believe it or not, idling actually causes more wear and tear than speeding down the highway at 70 mph. Vehicles are made to be driven, and prolonged idling can cause accelerated degradation due to low oil pressure, oil dilution, and incomplete combustion that can cause pesky carbon deposits. Excessive idling can also put some real strain on your fuel injectors, valvetrain, and other components, and should generally be avoided whenever possible. This is why many modern vehicles are equipped with stop-and-go technology or selective cylinder deactivation systems, designed to minimize idling.
Theft: There’s an important security concern associated with idling your vehicle, especially if you’re not parked in your own driveway or garage. Remote starters, whether on key fobs or smartphone apps, are certainly convenient, but there’s always going to be some danger associated with starting a vehicle that you can’t physically see. An idling vehicle can make a tempting target for a would-be thief, and is going to be all the more obvious on a cold day when they can spot the steamy tailpipe emissions from a mile away. While most of these remote starters don’t unlock the vehicle’s doors, there’s no reason to take any risks when it comes to one of your most valuable assets.
Legality: Theft is illegal, but many states have anti-idling laws that also make it illegal to warm up your car. Specific laws vary from state to state, or even county to county, but in many places, you’re not allowed to run the engine for more than a few minutes before setting off.
Play It Cool
Old habits die hard, but given what we now know about engine, oil, and fuel-injection technology, there aren’t many compelling reasons to warm up a newer vehicle before driving in cold weather. It might seem like an easy way to improve performance and efficiency or ensure a vehicle’s longevity, but the facts show that you’re really just wasting gas and the most precious resource: time. That said, drivers should always be mindful of safety and comfort when planning their pre-drive routine. Visibility is obviously a key factor when it comes to safe driving, and while it might not confer any concrete performance benefits, a warm, cozy vehicle certainly makes for a more enjoyable driving experience. Also, remember to take it easy within the first few minutes of driving and allow the engine to reach its normal operating temperature before attempting to overtake another vehicle or engaging in any other maneuvers that might cause you to accelerate rapidly.