Busted: 10 of the Most Common Car Care Myths

Introduction: In the world of car maintenance, misinformation runs rampant. From family “wisdom” to internet rumors, many car care myths get passed around without question. For instance, many drivers think premium fuel is always better, or that switching between synthetic and conventional oil will destroy an engine. And who hasn’t heard someone say a rough-running car “just needs a tune-up?”

As an experienced mechanic, I can tell you—don’t fall for these myths. Let’s clear the air and set the record straight so you can take better care of your car, save money, and avoid unnecessary repairs.

1. Premium Fuel is Always Better for Your Car

A common misconception is that premium fuel is inherently better for your car. In reality, premium fuel has a higher octane rating, which helps prevent detonation in high-performance or high-compression engines. But for most vehicles, regular fuel is all you need. If your car’s manual recommends regular gas, don’t waste money on premium—it won’t improve performance or fuel economy.

For cars with a recommended premium, it’s often safe to use mid-grade or regular fuel without significant impact. Modern cars will adjust to avoid knocking, but performance and economy could be slightly reduced. Stick to the recommended fuel type and save your cash.

2. Switching Between Synthetic and Conventional Oil Will Ruin Your Engine

It’s not true that you’re locked into one type of oil once you choose synthetic. Switching between synthetic and conventional oils is perfectly fine, as long as you follow the right viscosity. That said, synthetic oil offers superior protection and performance, and for long-term engine health, it’s often the best choice.

3. A Poorly Running Car “Just Needs a Tune-Up”

This myth has been around since the days of carburetors, when a simple tune-up could clear up performance issues. Modern cars, however, don’t work like that. While spark plugs still need replacing (usually after 100,000 miles or more), there’s no such thing as a “tune-up” on most new vehicles. A rough-running engine could be caused by anything from a malfunctioning sensor to a bigger mechanical issue. If someone tells you a car “just needs a tune-up,” be cautious—it might need much more than that.

4. Diagnostic Trouble Codes Tell You Exactly What’s Wrong

When the check engine light comes on, it’s tempting to assume that the diagnostic trouble codes (DTCs) tell the full story. While they point to potential problems, they don’t give a clear-cut solution. For example, a code for an oxygen sensor might not always mean the sensor is bad—it could be a vacuum leak or fuel mixture issue. Treat codes as a starting point, not a diagnosis.

5. Tightening the Gas Cap Will Immediately Fix the Check Engine Light

A loose gas cap can indeed trigger the check engine light, but there’s more to it than just tightening it. If the gas cap is the issue, the light won’t turn off immediately. You’ll either need to reset the system with a scanner, or wait until the vehicle’s computer verifies the problem has been fixed. Plus, there are many other reasons the check engine light can come on, and it may not be something as simple as a loose cap.

6. You Should Warm Your Engine Up for Several Minutes in Winter

Gone are the days when cars needed several minutes of warm-up time in cold weather. With modern fuel-injected engines, idling for more than a minute doesn’t help the engine. In fact, it wastes fuel and increases emissions. Of course, letting the engine warm up for comfort (e.g., to clear the windshield) is fine, but don’t idle unnecessarily.

7. A Misfire Means Bad Spark Plugs

If your car is misfiring, spark plugs are often the first thing people blame. While spark plugs can cause misfires if they’re worn out, they’re not always the culprit. Misfires can also be caused by faulty fuel injectors, ignition coils, or compression issues. It’s essential to troubleshoot the full system, not just assume the spark plugs are to blame.

8. Engine Overheating is No Big Deal

Movies make overheating look like a quick fix—just add some water and keep going. In reality, overheating can cause serious damage to your engine. If your temperature gauge climbs into the red, pull over immediately and turn off the engine. Continuing to drive can cause catastrophic engine failure, so don’t take chances.

9. It’s Normal to Top Off Coolant and Other Fluids

Many people think that topping off fluids like coolant or transmission fluid is a normal part of car maintenance. It’s not! If you’re constantly adding fluid, there’s likely a leak somewhere. Cars don’t burn coolant or transmission fluid under normal conditions, so if you’re topping them off regularly, it’s time to investigate and fix the issue.

10. Any Car Problem Can Be Solved with YouTube

While YouTube is a great resource for learning about car repair, it’s not a substitute for professional guidance or a repair manual. Every vehicle is different, and a fix for one model might not apply to yours. If you’re serious about DIY repair, invest in a proper repair manual for your specific vehicle or access a trusted service database. YouTube should only be used as a supplement, not a primary source.

Conclusion:

The bottom line is this—don’t believe everything you read or hear about car care. If you’re ever in doubt, consult a trusted mechanic or do some research. Avoiding these myths will help you save time, money, and frustration when it comes to maintaining your vehicle. When in doubt, always trust a professional to steer you in the right direction!