Your car is more than just a machine—it’s an investment, a lifeline, and a crucial part of your daily routine. If you want to keep it running smoothly for years to come, there are certain things you should never do. Some of these bad habits can lead to costly repairs, while others can put you in serious danger on the road. Let’s dive into 15 things you should never do to your car and how avoiding these mistakes can save you time, money, and frustration.
1. Never Ignore Rust—It Gets Worse Over Time
Rust is like cancer for cars. What starts as a small blemish can quickly spread, eating away at the metal underneath the paint. If you see bubbling paint or rusty spots, don’t ignore them. What looks like a minor issue on the surface is usually much worse underneath. Treat rust immediately by sanding, priming, and repainting the area before it becomes a major problem.
2. Never Overinflate Your Tires for Better Gas Mileage
Some drivers believe that inflating their tires above the recommended pressure will improve gas mileage. While it may reduce rolling resistance slightly, the drawbacks far outweigh the benefits. Overinflated tires lead to:
- A rougher ride
- Uneven tire wear
- Reduced traction, especially on wet roads
- Increased risk of tire blowouts
Always follow the manufacturer’s recommended tire pressure, which you can find inside the driver’s door frame.
3. Never Use the Wrong Coolant—It Can Wreck Your Engine
Your engine’s cooling system is designed to work with a specific type of coolant. Using the wrong kind or mixing different types can cause:
- Corrosion inside the cooling system
- Damage to the radiator and heater core
- Water pump failure
Always check your owner’s manual and only use the coolant specified for your car.
4. Never Mix Up Brake Fluid and Power Steering Fluid
This mistake happens more often than you’d think! While brake fluid and power steering fluid may look similar, they are not interchangeable. Pouring the wrong fluid into either system can lead to total brake failure or steering system damage, resulting in expensive repairs.
5. Never Use a “Universal” Transmission or Power Steering Fluid
Some aftermarket products claim to work in any vehicle, but car manufacturers have specific fluid requirements for a reason. The wrong transmission or power steering fluid can:
- Damage seals and gaskets
- Cause transmission slipping
- Lead to costly repairs
Always use the fluid recommended in your owner’s manual.
6. Never Disconnect the Battery Cable to Test the Alternator
Back in the day, you could test your alternator by disconnecting the battery while the engine was running. But modern cars are loaded with electronics, and doing this can send a surge of voltage through the system, frying expensive components like the ECU (Engine Control Unit). Instead, use a voltmeter to check your alternator’s output.
7. Never Ignore Your Oil Light—It’s a Warning, Not a Suggestion
If your oil light comes on while driving, pull over immediately. It could mean:
- Your engine is dangerously low on oil
- A major oil leak has occurred
- The oil pump has failed
Driving with low or no oil can destroy your engine in minutes, costing you thousands in repairs.
8. Never Drive With Less Than a Quarter Tank of Gas
You might think running your tank close to empty is no big deal, but it puts extra stress on your fuel pump. The pump sits inside the gas tank and relies on fuel to stay cool. Running low on gas repeatedly can cause premature fuel pump failure, leading to a costly repair.
9. Never Use the Wrong Oil in Your Engine
Modern engines have tight tolerances and advanced technology, like turbochargers and variable valve timing (VVT). Using the wrong oil viscosity can:
- Trigger a check engine light
- Reduce fuel efficiency
- Cause premature wear on critical engine parts
Stick to the manufacturer’s recommended oil—it’s designed to work best with your engine.
10. Never Wash Your Car With Dish Soap
Dish soap is great for cleaning greasy dishes, but it’s too harsh for car paint. It strips off protective wax, leaving the paint vulnerable to:
- Sun damage
- Fading
- Oxidation
Use a pH-balanced car wash soap instead to protect your paint’s finish.
11. Never Neglect to Check Your Oil Dipstick
Even if you get regular oil changes, your engine still burns some oil over time. Checking your dipstick at least once a month ensures your car always has enough oil. Running low can damage internal engine components and shorten its lifespan.
12. Never Leave Beverages in Your Car in Freezing Weather
Liquids expand when they freeze, and that unopened soda bottle or water jug could explode inside your car. Avoid unnecessary messes by taking beverages inside instead of leaving them in your vehicle overnight.
13. Never Smoke While Pumping Gas
This one should be obvious, but never light a cigarette or use a lighter near a gas pump. Gas vapors are extremely flammable, and one spark could start a fire or explosion.
14. Never Drive Without Shoes
It might seem comfortable, but driving barefoot reduces your ability to brake properly in an emergency. Shoes provide the grip and pressure needed for controlled braking. Plus, if you need to step out of your car suddenly, walking barefoot on rough pavement or hot asphalt won’t be fun.
15. Never Ignore Unusual Noises or Warning Signs
If your car starts making strange noises, vibrations, or warning lights pop up, don’t ignore them. Many small issues, like:
- Squeaky brakes (worn-out brake pads)
- Knocking sounds (possible engine trouble)
- Whining noise while turning (power steering issues)
Can quickly escalate into major repairs if left unaddressed. A quick inspection by a mechanic can save you a lot of money in the long run.
Final Thoughts: Take Care of Your Car, and It Will Take Care of You
Your car is one of your biggest investments, and treating it right can extend its life, improve performance, and save you thousands in repairs. By avoiding these 15 costly mistakes, you’ll ensure your vehicle stays reliable and road-ready for years to come.
What’s one bad car habit you’ve been guilty of? Time to break it and keep your ride running smoothly!
