Mechanics see the same bad advice damage cars again and again, and many of those mistakes start with myths drivers repeat as if they were fact. By cutting through these 10 car myths that mechanics beg you to stop believing, you protect your wallet, your engine, and your safety every time you turn the key.
1) Premium fuel always makes your car faster
Premium fuel always making your car faster is one of the most persistent myths, and it is flatly wrong for most vehicles. In a clip labeled “Myth one, premium gas makes your car faster,” a technician explains that if your engine is not built for higher octane, “you are literally donating money for no extra power,” underscoring that premium gas does not magically add horsepower. That means a Honda Civic or Toyota Corolla designed for regular unleaded will not accelerate harder just because you filled it with 93 octane.
Mechanics stress that the only time premium fuel matters is when the owner’s manual explicitly requires it for a turbocharged or high-compression engine. Otherwise, you are paying more per gallon for no measurable benefit in performance or longevity. Over years of commuting, that wasted money could have gone toward real maintenance like tires or brake service. Treat the warning that Myth one is costing you cash as a cue to follow engineering, not marketing.
2) Auto start/stop ruins your starter and wastes gas
Auto start/stop ruining your starter and wasting gas is another myth that refuses to die. In a breakdown of common misconceptions, one entry lists “Auto start/stop wears out your starter and uses more gas,” capturing exactly what many drivers fear when the engine shuts off at a red light. Mechanics counter that modern systems use reinforced starters, upgraded batteries, and software that limits cycling, so the hardware is engineered for this repeated on and off behavior.
Fuel use is also misunderstood, because idling at every intersection burns more gasoline than a brief, controlled shutdown. Over time, that extra idling can add up to gallons of wasted fuel and more emissions, especially in city traffic. If you still dislike the feel of the system, you can usually switch it off, but you should not assume it is destroying your car. The fact that “Auto” stop/start is singled out among car myths you should stop believing shows how far this misconception has spread.
3) Premium fuel improves performance in all cars
Premium fuel improving performance in all cars sounds similar to the speed myth, but it deserves its own spot because it affects how you budget for every fill-up. A detailed list of misconceptions calls out “Premium fuel improves performance in all cars,” highlighting how many drivers assume the most expensive option must be better. Mechanics explain that octane rating only measures resistance to knock, not quality, and engines calibrated for 87 octane cannot take advantage of 91 or 93 without specific tuning.
In practice, that means a family crossover like a Subaru Forester or Ford Escape will not gain extra torque or smoother running just because you choose the premium button on the pump. You are more likely to see a difference by keeping your air filter clean and your spark plugs fresh. Over thousands of miles, paying for “Premium” when your car does not need it can add hundreds of dollars to your fuel bill with no return. That is why experts group Premium fuel myths alongside other bad habits that Eff Car Habits tries to correct.
4) You must change your oil every 3,000 miles
You must change your oil every 3,000 miles is a myth left over from older engines and outdated lubricants. In a rundown of bad advice, one entry begins “You should change your oil,” then goes on to challenge the rigid mileage rule that many quick-lube shops still promote. Modern synthetic oils and tighter manufacturing tolerances allow many vehicles to safely run 5,000, 7,500, or even 10,000 miles between changes, as long as you follow the interval printed in your owner’s manual.
Mechanics warn that clinging to the 3,000-mile schedule wastes money and oil, and it can even encourage drivers to ignore more urgent needs like brake fluid or coolant because they feel “over-maintained.” Instead of relying on a blanket number, you should check the maintenance minder in cars like the Honda Accord or Chevrolet Equinox, which calculates oil life based on driving conditions. The key is that “You” should tailor service to your specific engine, not to a myth that no longer matches modern technology.
5) More frequent maintenance always means better reliability
More frequent maintenance always meaning better reliability sounds logical, but mechanics see the downside when drivers overspend on unnecessary work. The same list that warns “You should change your oil” too often also groups other over-servicing habits that do not match manufacturer schedules. When you replace parts like spark plugs, transmission fluid, or cabin filters far earlier than recommended, you are not automatically extending life, you are just increasing costs and the chance of mistakes during service.
Over-maintenance can also mask real problems, because you may assume a recently serviced system is healthy when an underlying issue remains. For example, repeatedly flushing coolant in a Subaru Outback will not fix a failing head gasket, and changing brake pads early on a Toyota Camry will not solve a sticking caliper. Mechanics urge you to follow the factory maintenance chart instead of inventing your own aggressive schedule. That way, your budget goes toward the work your car actually needs rather than chasing a myth that more is always better.
6) Online myths about algorithms only apply to tech, not cars
Online myths about algorithms only applying to tech, not cars, can mislead you about how digital information shapes automotive decisions. A guide to search misconceptions lists “Myth 1: Google Ranks Only Keyword-Optimized Content,” pointing out that many people still believe stuffing pages with phrases like “Google Ranks Only Keyword” and “Optimized Content” is the path to visibility. That same mindset shows up in car advice, where posts packed with “SEO” tricks and vague claims get attention even when the underlying guidance is wrong.
Because “Many” drivers now research repairs and maintenance online before visiting a shop, bad algorithm myths can translate directly into bad car myths. If you assume the top result is always the most accurate, you might follow unsafe brake bleeding instructions or accept false claims about oil additives. Mechanics want you to treat viral tips with skepticism, cross-checking them against your owner’s manual or a trusted technician. Recognizing that search results shaped by Google Ranks Only Keyword myths are not a guarantee of truth is a crucial step in protecting your vehicle.
7) Viral maintenance myths are harmless to follow “just in case”
Viral maintenance myths being harmless to follow “just in case” is a comforting idea, but it breaks down once you look at the costs. A video that urges viewers to “STOP Believing These 7 Car Maintenance Myths” frames them as “the biggest and most expensive car maintenance myths drivers still believe today,” making clear that the damage is financial as well as mechanical. When you act on every trending tip, you may buy additives your engine does not need, schedule services too early, or ignore factory procedures.
Mechanics see the fallout when drivers pour thick oil stabilizers into modern direct-injection engines or use abrasive cleaning methods on delicate sensors because a clip promised quick results. Even if the car survives, you have spent money and time on something that did not improve reliability. The warning from Eff Car Habits is that myths are not neutral; they can quietly drain your budget and shorten component life. Treat every “hack” with the same scrutiny you would apply to medical advice.
8) Mechanics are just trying to upsell when they debunk myths
Mechanics are just trying to upsell when they debunk myths is itself a misconception that keeps drivers from hearing good advice. When a technician explains that premium gas is a waste for your engine or that 3,000-mile oil changes are unnecessary, they are actually talking you out of spending money, not into it. The clip that starts with “Myth one, premium gas makes your car faster” is a perfect example, because the speaker is telling you to buy cheaper fuel when your car allows it.
Distrust can grow when you have had a bad experience at a chain shop, but independent mechanics often use myth-busting to build long-term relationships. By steering you away from unnecessary services, they free up your budget for critical repairs like timing belts or safety recalls. When you assume every correction is an upsell, you may cling to bad habits that cost more over time. Listening carefully when a professional dismantles a myth can be one of the simplest ways to save money and extend your car’s life.
9) All car myths are obvious and easy to spot
All car myths being obvious and easy to spot is a comforting belief, but it does not match how misinformation actually spreads. The list that includes “Auto start/stop wears out your starter and uses more gas” and “Premium fuel improves performance in all cars” shows that even plausible-sounding statements can be wrong. Both claims feel intuitive, because more starting cycles seem harder on parts and higher octane sounds like higher quality, yet mechanics and engineers repeatedly explain why those assumptions fail.
Subtle myths often hide inside partial truths, such as “You should change your oil” without specifying the correct interval for your engine. Drivers who consider themselves knowledgeable can still fall for these half-right ideas, especially when they are repeated by friends or influencers. Recognizing that myths are not always ridiculous is the first step toward questioning them. When a claim about your car sounds reasonable, you should still verify it against technical documentation or a trusted shop before changing your routine.
10) Once debunked, a car myth disappears for good
Once debunked, a car myth disappearing for good is wishful thinking that underestimates how stubborn bad information can be. The fact that “Auto start/stop wears out your starter and uses more gas,” “Premium fuel improves performance in all cars,” and “You should change your oil” on a rigid schedule all appear together in a modern roundup proves these ideas are still circulating. Mechanics report hearing the same lines from new generations of drivers who picked them up from relatives, social media, or outdated articles.
Because myths keep resurfacing, you need to treat car knowledge as something to revisit, not a one-time lesson. When a new model year of a Ford F-150 or Hyundai Tucson introduces different oil specs or fuel recommendations, old rules may no longer apply. Checking current guidance and being willing to update your beliefs protects you from clinging to advice that fit carbureted engines but not today’s turbocharged, computer-controlled cars. The persistence of these myths is exactly why professionals keep begging drivers to stop believing them.
More from Wilder Media Group: