As a former mechanic, I can tell you that there are many things that can go wrong, especially if you have bad habits when it comes to maintenance. Of course, ignoring maintenance altogether is always a bad thing. But some people mean well and still wind up doing more harm than good. Whether you’re topping off fluids too often or warming up your engine longer than needed, certain routines may be costing you more than you realize. These nine car maintenance habits are doing more harm than good.
1. Overfilling Your Oil
At one point in time, my wife was just shoving more oil in her car because she thought it was leaking. More isn’t always better, especially when it comes to the oil in your vehicle. Overfilling it can cause excessive pressure, which can cause leaks, blown seals, and even engine damage. Going over the max line on the dipstick can (and will) disrupt the lubrication process. This could cause the oil to foam, which reduces its overall effectiveness. When it comes to oil levels, stick to what your owner’s manual says!
2. Warming Up the Engine Too Long
Idling your car in the driveway for 10 or 15 minutes might feel like you’re doing it a favor, especially on cold mornings. But modern engines are built to warm up faster when you’re actually driving, not sitting still. Extended idling wastes fuel, increases emissions, and can cause unnecessary wear. A better approach is to let your car idle for 30 seconds to a minute, then start driving gently. This gets your engine and transmission up to temperature more efficiently.
3. Using the Wrong Fuel Grade
If your car doesn’t require premium fuel, putting it in is more of a waste than an upgrade. Some drivers think higher-octane gas gives better performance or keeps the engine cleaner, but that’s not true for most vehicles. Using premium in a car that only needs regular offers no benefits, and just drains your wallet faster. In some cases, it could even harm engine components over time. Always follow the fuel grade listed in your owner’s manual.
4. Ignoring the Check Engine Light
That little amber light on your dashboard isn’t just a suggestion—it’s a warning that something isn’t right. Some drivers choose to ignore it, assuming it’s just a sensor glitch or not urgent. But delaying diagnostics could turn a minor issue into a major (and costly) repair. In some cases, it can even lead to engine failure or decreased fuel efficiency. If that light pops on, get it checked out promptly—even if your car feels like it’s running fine.
5. Washing Your Car With Dish Soap
It’s tempting to grab the nearest bottle of dish detergent to wash your car, but this is a classic mistake. Dish soap is designed to cut through grease—and it’ll also strip away your car’s protective wax coating. Over time, this leaves the paint vulnerable to fading, oxidation, and corrosion. Always use car-specific soaps that are pH balanced and gentle on paint and sealants. That extra care helps preserve the look and value of your vehicle.
6. Skipping Tire Rotations
Tire rotation might seem like one of those optional maintenance tasks, but skipping it can cost you in the long run. Tires wear unevenly depending on their position, and without rotation, you may find yourself replacing them more often. Uneven wear can also affect your car’s handling and fuel efficiency. Most manufacturers recommend rotating your tires every 5,000 to 7,500 miles. Keep this on your radar if you want to get the most life out of your tires.
7. Topping Off Fluids Excessively
Just like with motor oil, over-topping other car fluids—like brake fluid, coolant, or transmission fluid—can do more harm than good. Many systems are designed to work under specific pressure levels, and adding too much fluid can cause leaks or damage seals. Always check your levels when the car is cold and on a level surface, and only fill to the indicated “max” line. More isn’t always better—it’s about balance. Check the manual before adding anything to your system.
8. Resting Your Hand on the Gear Shifter
It might seem harmless to rest your hand on the gearshift while driving, especially in manual transmission cars. But over time, this can apply unnecessary pressure to internal components of the transmission. This added stress may cause premature wear to the shift forks and other parts. If you want to avoid costly transmission repairs, keep both hands on the wheel when you’re not actively shifting gears. It’s a small change that can make a big difference.
9. Ignoring Strange Noises
If your car starts making unusual sounds—squealing brakes, grinding gears, or knocking under the hood—it’s not something to brush off. These noises often signal issues that need immediate attention. Waiting too long can allow small problems to worsen and spread. Pay attention to new or worsening sounds and get them checked out by a trusted mechanic. Catching problems early often saves you from a massive repair bill later.
Be Smarter Than Your Habits—Drive With Awareness
Bad car maintenance habits are easy to fall into, especially when they seem harmless or even helpful on the surface. But over time, these missteps can damage your vehicle and drain your finances. Fortunately, just being aware of what to avoid is a huge step toward protecting your investment. Think of your car like any long-term relationship: a little care, done the right way, goes a long way.
What surprising car habit did you think was helpful until now? Share your thoughts in the comments!
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