When it comes to taking care of your vehicle, you need to be able to trust your mechanic. However, you should also be aware of what repairs and modifications aren’t necessary. In some cases, they could even hurt your car’s safety and longevity. Here are ten fixes you should be wary of if your mechanic suggests them.
1. Engine Flushes
As a former Porsche technician who worked hands-on in the automotive industry for over 15 years, I can tell you that engine flushes are a joke. There is nothing you can pour into your engine to fix an issue. Products like Seafoam are snake oil, and all the smoke from the back isn’t removing carbon. It’s burning the junk you sent through the intake system or into the engine oil. Shops are approached by salespeople who claim their products do this or that, like any good salesman, but shops stock these products as an upsell item to turn a $100 oil change into a $200 one.
2. Replacing the Transmission Without Diagnosis
It is a complicated and expensive job to replace your transmission. Often, mechanics will jump at the chance to offer a transmission replacement when less costly repairs could be made to fix the issue. The mechanic might not spend time diagnosing the problem, which can lead to a more expensive bill. Before you proceed with a transmission replacement, ensure it has been thoroughly diagnosed. It’s not a bad idea to get a second opinion for these more expensive jobs, either.
3. Unnecessary Brake Pad and Rotor Replacements
Your car’s braking system is one of the most critical maintenance items, and you should have inspected it regularly because your brake working can mean the difference between life and death. Unfortunately, many unscrupulous mechanics know this and may try to tell you that you need new brake pads and rotors before you actually do. This is mainly because, in the mechanic world, brakes are an easy job that pays well and is commonly referred to as “gravy work.” Brake pad thickness is measured in millimeters and only needs to be replaced once it reaches a certain threshold. If a mechanic tells you your brakes need replacement, ask them to show you on the car and have them measure the thickness in front of you.
4. Fuel Injector Cleanings
Many shops offer fuel injector cleaning as a common service, claiming it can improve fuel economy and efficiency. However, this is almost never necessary. Modern engines use direct fuel injection, where the fuel is sprayed directly into the combustion chamber instead of the intake manifold like in the past. To push the fuel past the pressure of combustion, the fuel is delivered at an extremely high pressure, which allows the injectors to clean themselves effectively. If you have a car built in the last 10 years and have a rough idle or poor fuel economy, it is more likely that you need a carbon-clean rather than anything being wrong with your fuel injectors.
5. Premium Oil Changes
Changing your car’s oil is a routine maintenance item that you should perform roughly every 5,000 miles. Many auto manufacturers claim that their vehicles can go seven, eight, or even 10,000 miles without an oil change, but I can tell you, as a mechanic for over 15 years, you should never let it go that long, even with modern synthetic oils. What you don’t need to pay for is what some shops call a “premium oil change,” which consists of some “flush” and oil additives added to the new oil. Among mechanics, we call all these additives “snake oil” because there is nothing you can pour into your engine to fix a problem. But it allows them to upcharge for a basic service that is relatively cheap.
6. Replacing Air Filters Too Frequently
Your engine’s air filter is part of the air induction system and needs to be replaced according to the manufacturer’s recommendations. This can vary depending on the make, model, and engine type. Normally, this service should be performed every 10,000 miles or so, but if you live on a gravel road or anywhere where there is a lot of dust in the air, it could be shorter than that. On most cars, this is another example of “gravy work” that pays more book time than it actually takes to perform. Unless you drive a Porsche Panamera because the air box is located under the front bumper, and you basically have to disassemble the entire front of the car to access it.
7. Replacing the Entire Exhaust System
Modern vehicle engine exhaust systems are much more complex than they used to be. Common symptoms of exhaust issues are a rattling sound coming from under the vehicle, excessive noise, or poor running quality. Since the exhaust system has become more complex, most manufacturers break the exhaust into sections starting from the headers or downpipe turbo vehicles, then a catalytic converter, a middle section with a resonator, and finally, the actual muffler at the car’s rear. If a shop tells you that your entire exhaust system needs replacement, it is likely a scam because almost any issue can be resolved by replacing a single section.
8. Unnecessary Timing Belt Replacements
Timing belts are becoming less and less common as timing chains are more reliable and allow the engine to be more compact. However, timing belts are not extinct and are still used on many Toyotas, Hondas, and Hyundais. The average service interval for timing belts is typically between 60,000 and 100,000 miles, depending on the manufacturer. If a shop offers you a timing belt service well under these margins, there is either damage to the belt, or they are trying to scam you. On the other hand, if your vehicle has a timing chain and a shop is recommending a service, they probably know something you don’t. I would strongly consider it because ignoring cars with timing chain issues, such as Volkswagens from the 2010s, could cause catastrophic damage.
9. Over-the-Top Suspension Repairs
In modern vehicles, the suspension system has many moving parts, mostly rubber bushings. Over time, these bushings wear out and need replacement, but this typically occurs well into a vehicle’s life. The first things to go bad are shocks, struts, and airbags if the car has an air-operated suspension. Modifications such as larger wheels and tires can speed up this process and affect other components, such as the lower control arms. That said, unless your car is 20 or 30 years old, it is improbable that it will need significant suspension repair. I would seek a second opinion if a shop tells you your vehicle needs them.
10. Battery Replacements That Aren’t Needed
Your vehicle’s battery is a maintenance item that most people forget about. They assume there is no issue as long as they get in the car and it starts. The average life of a car battery is 3 to 5 years, depending on the climate and type of battery used. If your vehicle is slow to start, as a mechanic, I admit the battery is the first thing you test. Your car needs 12 volts of electricity to start, and if your battery is producing less than that, it is either old and not accepting the charge from the alternator, or the alternator is not producing the 14.9 volts needed to run the vehicle and effectively charge the battery. If a shop automatically says your car needs a battery, ask them to show you the test results because most testers print out a slip of paper that tells you exactly how much charge your battery has and how much power the alternator produces.
Find the Right Mechanic
The most important thing when having your car serviced is finding a mechanic you can trust. When I was a Porsche technician, my customers followed me from shop to shop because they completely trusted me. I never tried to sell them anything they didn’t need, and if their car had a lot of problems, I would prioritize dangerous items over items that could wait. Not all mechanics have that type of character, and when you find one that does, do your best to stick with them.