The Worst Car Maintenance Tips You’ll Ever Hear In Your Life

The Worst Car Maintenance Tips You’ll Ever Hear In Your Life

Everyone seems to have a piece of car maintenance advice: a relative who has “always done it this way,” a viral TikTok hack, or a stranger online promising that a $10 shortcut can save you hundreds at the repair shop.

The problem?

Cars have changed, and advice that worked for one vehicle, or sounded reasonable decades ago, may be completely wrong for yours.

Bad maintenance advice can lead to:

• Using the wrong oil, coolant, fuel, or other fluids.
• Ignoring dashboard warning lights because the car still seems to drive normally.
• Delaying tire, brake, battery, or fluid maintenance for too long.
• Using DIY products or “hacks” that aren’t recommended for your vehicle.
• Following universal service intervals instead of your manufacturer’s car maintenance schedule.
• Creating problems that could affect repairs, warranties, car insurance claims, or your safety on the road.

This is particularly important for a beginner driver or someone maintaining a first car.

You shouldn’t need to become a mechanic, but knowing the difference between sensible car care and questionable advice can help you avoid expensive mistakes.

So before trying that clever maintenance trick someone swears has worked for 20 years, check your owner’s manual and ask one important question: Is it actually appropriate for my car?

Here are some of the worst car maintenance tips you should think twice about following.

Use Dish Soap To Clean Your Car, It’s Cheaper

Dish soap is cheap, and that’s a good thing. You don’t want to spend a fortune every time you do a bit of washing up.

But using it in your car is not advisable. Why? Simple: modern car paints contain elements that dish soap can potentially harm.

For instance, many manufacturers include small amounts of wax in their formulations, designed to give vehicles extra sheen.

Dish soap contains factors that strip this wax from the surface of your vehicle, leaving it looking dull and lifeless over time.

Sure, washing your car with dish soap once or twice during its lifetime probably won’t make much of a difference.

But doing it continuously will eventually lead to damage to the external shell.

Letting The Rain Wash Your Car For You

Just because rain is wet doesn’t mean that it’s cleaning your car thoroughly.

What’s more, downpours sufficient to actually have an effect might not come along very often.

During the intervening period, dust, pollen, and dirt have time to accumulate and eat away at the bodywork underneath.

Remember, nature constantly tries to turn your vehicle to dust, reducing its value. So leaving dirt on the exterior is never a good idea.

Eventually, it will cause harm. If you want more valuable tips for your vehicle, you should follow this winter car maintenance checklist!

To prevent this, take your vehicle to the car wash at least once per month.

Ideally, you’ll want to clean it from top to bottom every few weeks.

Don’t forget to wash your car in the winter as this is a time when salt from the road can cause additional corrosion.

Turning Up The AC To Cool A Sweating Engine

This advice is downright funny because it has the opposite of the intended effect.

Running your air conditioning actually heats up your engine more because the excess heat has to go somewhere.

It doesn’t just disappear.

Think about it. When you switch the air conditioning on, you pass air through a refrigeration unit which cools it.

Refrigerants which now contain the transferred heat circulate around the vehicle to various radiators where they emit their heat to the surrounding environment.

The car’s cabin cools down, but the radiators heat up. And since most of them are close to the engine, they can make things worse.

The good news is that the opposite of the above advice might help you if your engine is starting to sweat.

Try turning on the air vents in the cabin without engaging the AC. This way, you’ll transfer hot air out of the engine and onto your face. Great in winter, not so good in summer.

Set Tire Pressure Based On The Imprint

If you look at the side of your car’s tires, you’ll notice that they have an imprint, telling you the maximum PSI or BAR. Note the use of the word “maximum.”

This is the top pressure that the tires can accommodate, not the recommended inflation level.

Don’t follow it.

Instead, if you think you need to pump up your vehicle’s tires because they’re looking a little low, check the manual that came with your car.

This should tell you how much you need to inflate. If you over-inflate, you’re much more likely to experience a blowout.

Just driving over a speed bump could lead to an explosive flat.

Use Hot Water To Defrost The Windshield

Using hot water to defrost the windshield is one of the craziest pieces of advice that you’ll ever hear.

The idea is to boil a kettle and then pour it over any frosted up sections of your vehicle. Hot cancels out cold, right?

Well, not so fast. It turns out that pouring hot water on a windshield that’s been cold all night can cause thermal shock.

Some parts of the glass expand faster than others, leading to points of stress that could cause cracking.

Try using a defroster instead. This is a much more sensible approach since it doesn’t rely on the use of heat.

Instead, it uses chemicals to lower the freezing point of water, so any existing frost turns to liquid.

Flushing Your Engine With Water

You sometimes hear of dodgy dealerships in lemon law cases flushing engines with water.

The idea is to purge all the “bad stuff,” as some sort of medieval exorcism.  However, that’s not how engines work.

Infact, flooding them with water is one of the worst things that you can do. After all, engines rely on combustion, and water has a knack for putting out flames.

If you attempt to flush your engine with water, you’ll destroy it. It probably won’t turn back on.

And even if it does, it’ll feel clogged. Instead, if you need to flush it out, take it to a mechanic.

They’ll be able to make various recommendations.

Investing in a Beaten-Up Classic

Buying a neglected vintage vehicle for a bargain price and restoring a classic car to its former glory sounds like the perfect weekend project.

Restoration shows can make the transformation look surprisingly straightforward, but the reality can be very different.

One of the biggest mistakes to avoid while buying a classic car is focusing on the purchase price while underestimating what comes afterward.

A cheap project car can become expensive once you discover hidden rust, electrical problems, engine damage, missing trim, or parts that are difficult to source.

If you’re buying a classic because you genuinely love the vehicle and the restoration process, the time and expense may be worth it.

If you’re treating it primarily as an investment, however, do the numbers before falling in love with the car.

This is especially important if your original goal was to find used cars with low maintenance costs. An inexpensive purchase price doesn’t necessarily mean inexpensive ownership.

Older vehicles can require harder-to-find parts, specialist labor, more frequent repairs, and ongoing restoration work that quickly changes the financial equation.

A specialist inspection before purchase can help you understand what you’re actually buying, and whether that “bargain” is genuinely one of the used cars with low maintenance costs you’re looking for or an expensive restoration project hiding behind an attractive price.

So, which of these bad car maintenance tips have you heard before?

More importantly, are there any you’ve been guilty of trying yourself?