10 harmful misconceptions about car maintenance

There is a lot of advice out there from friends, family, and car manufacturers about fuel economy, engine power, and overall vehicle longevity. But not all of it is true. Here are 10 common misconceptions about car maintenance.
1. You need to change the oil every 3,000 miles (4,800km)

In automotive experience, this was true in the past, but many oil companies and oil stores still promote this idea. Now, most cars made in the last decade only need an oil change every 5,000-7,500 miles (8,000-12,000km), depending on the manufacturer.

Today’s cars have better chemistry, widespread use of synthetic oils, and superior engine designs that reduce the number of oil changes. Your oil change schedule should be based solely on your owner’s manual. Otherwise, you’re just throwing money down the drain.

2. Premium fuel is better for your car and increases performance

This is only true for vehicles with high compression and high efficiency engines. For civilian vehicles, regular gasoline will work just fine. Cheaper 86 octane fuel still has to meet quality standards and will not harm the vehicle's engine.

Sports cars often use higher octane fuels that include detergents and preservatives to keep the turbocharged engine in better condition. Regular gasoline will be fine for mid-priced cars.

3. Vehicle maintenance at non-genuine repair shops will void the warranty.

The vehicle warranty is valid until the expiration date, regardless of where you service the vehicle. Authorized dealers prefer that owners only come to them, but they don't force them to.

Any maintenance on a vehicle that is still under warranty can be done at any auto repair shop. All you need to do is keep your receipts to show what was done and how much it cost.

4. Warm up the engine before driving in cold weather

Engine parts need to warm up to function properly, but modern engines warm up more quickly while you're actually driving. Also, bearings and transmissions only fully warm up when the car is moving.

Therefore, there is no benefit to idling your car for a while before driving in cold weather other than to warm up the interior of the car. Fuel consumption and performance are only affected by usage. Therefore, idling is basically a waste of money and fuel.

5. You should replace all four tires at the same time.

In fact, car owners only need to replace individual tires as needed as long as they are the same brand, model, and size. To maximize longevity, just make sure to remove the tires at every oil change.

Also, you don't necessarily need to buy new tires if you get a flat. A patch is enough because the patch will keep moisture out of the steel rim and restore the tire's seal.

6. Wash your car with laundry soap or dishwashing liquid

At first glance, this may seem like a good way to save money. However, washing your car with laundry soap or dish soap actually damages the wax finish of your car.

Instead of contributing to rust stains, pay a little extra for a specialized car wash fluid that is designed not to damage your car's protective wax coating.

7. The battery will be recharged after a short period of driving.

It takes hours of driving to fully charge a car battery, especially in cold weather. Car accessories like heated seats, radios, and lights draw a lot of power from the alternator, so even a short drive could leave your car with a dead battery the next time you drive.

8. Transmission fluid must be changed every 50,000 miles (80,000km).

Although it is generally recommended that customers change their transmission fluid every 50,000 miles, most modern vehicles use a long-life transmission fluid. Today’s fluids are designed to last up to 100,000 miles or even the life of the vehicle. This can vary from vehicle to vehicle, so always consult your vehicle manufacturer’s instructions.

9. Open windows instead of using air conditioning to save fuel better

In reality, rolling down the windows or turning on the air conditioning makes little difference in fuel economy. It's true that turning on the air conditioning burns fuel faster. However, opening the windows also increases wind resistance.

As a result, the car will need to burn a little more fuel to compensate for the broken aerodynamic design. The overall impact of opening the windows or turning on the air conditioning on fuel economy is minimal. Neither option really offers any advantage.

10. Filling up in the morning saves money on gas

Gasoline expands with heat, so many people believe that filling up with warmer fuel means getting less fuel. In theory, pumping fuel in the morning will be cooler, allowing for more fuel at a lower cost.

However, this is not the case. Gasoline is typically stored underground and insulated from temperature changes, so the timing of your fill-up doesn't really make a difference to the amount of fuel you get.