7 Car Maintenance Myths Debunked

A man smiling and standing in front of his vehicle with his arms crossed.

There has always been a hint of skepticism surrounding the auto industry. Alexander Winton — the first man to build and sell a gas-powered vehicle in America — was once ridiculed by his banker as “another inventor talking.” And while Mr. Winton’s ideas have won out, the public’s skepticism of certain claims remains. In spite of genius inventions and solid advice, there are a lot of car maintenance myths that give real experts a bad name.

To help you save money on vehicle maintenance and not spend where you don’t need to, this blog will explore and debunk seven popular car maintenance myths. 

Why Debunking the Myths Matter

Car owners can often end up on two ends of the spectrum: the ones who throw their money away on unnecessary maintenance, and the others who stay away from routine maintenance altogether.

However, it’s important for the average driver to know what they need and what just doesn’t matter all that much. We also believe it’s the job of a skilled automotive professional to help the average vehicle owner know how to wade through the myths and misconceptions. Why? So you can better make your own educated decisions surrounding your vehicle.

A mechanic standing inspecting a vehicle engine and writing on his clipboard.

7 Popular Car Maintenance Myths

#1 The 3,000 Mile Oil Change Interval Myth

Like a lot of myths, there’s some truth to this one. The myth,  which states all motor vehicles should have their oil changed at least every 3,000 miles — was once more applicable to vehicles than it is today.

Modern vehicles — those made in the past 10 to 15 years — are able to run for at least 5,000 miles before needing an oil change, and modern vehicles with synthetic oils can last even longer. Most importantly, every vehicle owner should consult their manufacturer’s recommendations for how often their specific vehicle model should have its oil changed.

#2 Miscellaneous Engine Oil Myths

Perhaps no aspect of a vehicle has more myths and opinions surrounding it than motor oil. To dispel a few popular myths, below are three common misconceptions you may have heard before:

  1. You can’t mix synthetic and conventional oil. Synthetic and conventional oils have the same basic components: base oils and additives. While the base oils and additives in synthetic oil are often cited as superior to their conventional counterparts, they can still be mixed with each other with no harm done.
  1. Once you switch to synthetic oil you can’t go back. It’s perfectly safe to switch from conventional oil to synthetic oil. Once again, the two are compatible.
  1. Motor oil must be changed once it’s turned black. This isn’t necessarily true. Motor oil will naturally darken as your engine runs. Also, detergent and dispersant additives hold contaminants in suspension and prevent them from adhering to engine parts, which can cause engine oil to turn black. 

Instead of scrutinizing the color of your oil, it’s always best to consult your manufacturer’s recommendations.

#3 Car Battery Myths And Facts

There are more than a few myths surrounding car batteries. Three common ones include:

  1. Driving your vehicle will recharge a weak battery. Simply driving for any period of time will not fully recharge your battery, as starting your vehicle puts a strain on the battery. The only proper way to recharge a flat battery is with a multi-stage battery charger.
  1. Letting a vehicle idle will recharge a weak battery. Letting your vehicle idle for any period of time will not fully recharge your battery — and it could even shorten its life. A better option is to connect a maintenance charger to keep your battery in proper working condition.
  1. A flat battery has no effect on fuel economy. A flat battery causes your vehicle’s alternator to work harder, which can mean poorer fuel economy. This happens because of the extra load added to your engine which in turn uses more fuel.

#4 Air Filter Gas Mileage Myth

This is another car maintenance myth that once had some truth to it. Back when every vehicle had carburetors, a dirty air filter would affect fuel economy. The reason being that when the air was restricted on the carburetor, there wasn’t really any way to limit or shut down the amount of fuel going into the engine, since the carburetor was mechanical.

Since modern vehicles operate off of fuel injection, a device on the back of your vehicle’s air filter measures the amount of air coming through the air filter. Your vehicle has a computer that knows how much air is coming in and mixes the proper amount of fuel to maintain a proper air/fuel ratio.

A person cleaning a headlight using an orange towel.

#5 Wd40 Headlight Myth

This myth has to do with restoring your vehicle’s headlights. Over time, headlights can become covered with oxidation as the sun beats down on your vehicle. This not only looks bad but it begins to degrade the plastic over your headlights over time.

One of the ways to clean up your lenses, as some people may tell you, is the WD-40 method. While not completely a myth — as it will clean them up for a short period of time — it’s not a great long-term choice. If you’re looking for a quick shine, then it certainly won’t hurt your vehicle to do so. 

Ultimately, old headlights should really be replaced, new headlight covers are a good choice when your headlights are still functioning properly but your covers are beyond a little TLC.

#6 You Should Warm Up Your Vehicle Before Driving In the Cold

Modern engines actually warm up faster while driving. Additionally, wheel bearings and transmission require movement to properly warm up — so running your vehicle idle before driving in the colder weather has no benefit other than heating up the inside of your vehicle.

Also, since idling your vehicle in your driveway uses gas to go nowhere, you’re essentially wasting money and fuel for no reason.

#7 Roll Down Your Windows and Turn Off AC for Better Fuel Economy

Turning off your AC and rolling down your windows makes little difference toward fuel efficiency. While rolling down the windows can increase wind resistance — meaning your car may burn slightly more fuel to compensate for its disrupted aerodynamic design, the overall impact of both AC or rolled-down windows is extremely minimal.

While not exhaustive, this blog does debunk a lot of popular money-wasting car maintenance myths that could otherwise make owning and operating your vehicle more expensive and less enjoyable than it should be.

For more information on routine maintenance, visit our FAQs page or contact us to schedule an appointment with your local K&W store.