5 car maintenance myths debunked

By Allstate

Last updated: January 1

As a car owner, you've likely heard different things about maintaining your vehicle, whether it's how often you need service, to the best way to use your air conditioning. But that conventional wisdom may not always be correct. Here are five common car maintenance myths, and the truths behind them.

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Myth #1: Transmission fluid should be flushed.

Mechanics sometimes recommend transmission service and fluid changes as frequently as every 50,000 miles, according to Cars.com, but is it necessary? Consumer Reports says usually not. Most modern vehicles use "long-life" transmission fluid that is designed to last for 100,000 miles or sometimes for the life of the vehicle. Since vehicles can vary, consider following the manufacturer's recommendation as to how often to change your transmission fluid, says Cars.com.

Myth #2: Using the air conditioner is better for fuel economy than opening the windows.

It's difficult to say for sure, because fuel economy can vary depending on your vehicle. Some people think that opening your car's windows increases drag. But Consumer Reports tested this theory and determined that rolling down the windows at 65 mph did not noticeably reduce fuel economy.

And while running the AC may reduce fuel economy by 1 to 4 mpg according to Consumer Reports, the site recommends using it because it dehumidifies the car's interior, which may help keep the driver alert.

Myth #3: High-octane premium fuel is better for all engines.

When it comes to your car's fuel, premium doesn't always mean better. Unless your vehicle's owner's manual specifically states that your car requires premium fuel, it may not be necessary, Consumer Reports says. You can avoid the extra cost for premium fuel if your vehicle doesn't require it.

Myth #4: Driving a dirty car improves fuel economy.

Some drivers believe that dirt particles on the surface of a vehicle reduce wind resistance and improve fuel economy — in the same way dimples on a golf ball can reduce wind resistance. It turns out the opposite is true: Dirt on your car is randomly distributed, and that decreases fuel economy by about 10 percent, according to MythBusters. Keep your car clean to help maximize gas mileage.

Myth #5: Filling up your tank in the morning will save you money on fuel.

Does fueling in the morning mean more bang for your buck? Because gasoline expands with heat, some drivers believe that pouring warm or heated fuel into your car ultimately means you're getting less fuel. So, cooler morning temperatures would mean denser — and therefore, more — fuel (or so the myth says). But gasoline is typically stored underground, which insulates it against drastic temperature changes, according to Investopedia. Ultimately, it doesn't matter what time of day you refuel your vehicle, the site concludes.

Now that you know the truth behind these five myths, you may help maintain your vehicle with confidence. Looking for more tips? You may want to consider these car maintenance tips to help keep your car in good shape all year long.