Putting Toothpaste In Gas Tank

A clean white smile boosts your confidence and prevents tooth decay. That’s why the American Dental Association recommends brushing your teeth twice a day with a high-quality toothpaste like Colgate. Yet they remain entirely silent on the topic of putting toothpaste in your gas tank.

However, internet clickbait ads are rife with strange ideas to help improve people’s fuel economy. Not the least of which is a viral ad circling around that shows someone putting Colgate toothpaste in their gas tank, claiming that you can save $2 per gallon on your fuel bills.

Unfortunately, the internet has become possessed by this demonic idea, luring a few unwise people to try it only to suffer the disastrous consequences to their car’s fuel system, engine, and other components. To help exorcise the demons of minty fresh fuel tanks, we don’t need a young priest and an old priest; we just need to look at the commonsense chemistry of your car’s fuel system.

What’s In Toothpaste?

Toothpaste is an amalgam of things like Propylene glycol, sodium bicarbonate, sodium pyrophosphate, anhydrous dicalcium phosphate, dioctyl sodium sulfosuccinate, and other oral chemistry ingredients. None of these are designed to run through a car’s fuel system, oil, or engine.

Adding to its incompatibility with internal combustion engines is the fact that toothpaste has miniscule abrasive particles that create friction on the surfaces of your teeth. On the end of a toothbrush, this helps scrape away plaque and surface stains from tooth enamel.

Internal combustion engines rely on oil to act as a lubricant to minimize friction. So, even before toothpaste meets the fuel tank, oil and toothpaste are at cross purposes.

4 key Effects of Putting Toothpaste in the Gas Tank

Adding toothpaste to your gas tank or any other part of your fuel system can have disastrous consequences. Not the least of which is clogging your fuel filter, fouling your fuel pump, and contaminating other important engine fluids. You also have to consider that gasoline acts like a solvent, separating many of toothpaste’s ingredients as they slosh around in the tank.

1. Clogging the Fuel Filter & Fuel Pump

Clogging the Fuel Filter & Fuel Pump

Your car’s fuel system relies on a series of filters, starting with the fuel filter, to keep gasoline or diesel flowing smoothly through the system. When you add toothpaste to the gas tank, the abrasive particles and other particles settle like sediment. Other gelatinous ingredients in toothpaste, like sorbitol and glycerol, can congeal to act a lot like tank varnish.

Depending on how much toothpaste you put in your gas tank, it can gradually clog the fuel filter and strain the pump. This will happen even faster if you have a low amount of gas in the tank, sucking more of the toothpaste contamination into the system at one time.

2. Clogging the Fuel Lines

Clogging the Fuel Lines

If your fuel filter was clean and your fuel pump was in good condition when you added the toothpaste to your gas tank, some might pass through to obstruct your fuel line. This could happen just about anywhere in your fuel line. However, it’s most likely to cause a clog in the engine’s fuel rail right before entering the fuel injectors.

3. Corrosion in the Fuel System

Corrosion in the Fuel System

The water content and other chemicals in toothpaste can also cause corrosion in your fuel tank. Once it separates out from the physical chemistry and micro-abrasives, the water can then interact with things like the fuel filter, fuel pump, or the fuel-sending unit, causing corrosion.

4. Interfere with the Gas Gauge

Interfere with the Gas Gauge

A big blob of fresh toothpaste in your gas tank can easily slosh onto the fuel-sending unit, causing it to send an inaccurate reading to the gas gauge on your display console. It gums up the moving parts that read the fuel level, possibly sticking the fuel-sending unit at the level it was when you added the gas tank.

6 Things Can be Damaged In Engine By Toothpaste

Let’s imagine the worst-case scenario happened, and some toothpaste or some of its separated base ingredients made it past the fuel filter to enter your engine through the fuel pump and fuel lines. This can cause a whole new level of problems, such as contaminating the oil, affecting the lubrication of the engine’s moving parts, and clogging fuel filters. Just to say the least.

1. Clogging the Fuel Injectors

Clogging the Fuel Injectors

Fuel filters have tiny ports with little solenoids in them that can be easily clogged by toothpaste and its base ingredients. Micro abrasives and gelatinous lumps caused by the separated humectant in the toothpaste can potentially clog the solenoids, causing one or more fuel injectors to stay closed or wide open.

2. Misfires


If one or more fuel injectors are fouled by toothpaste in the gas, it can then cause a massive imbalance in the fuel/air mixture in the cylinders, leading to a misfire. Excess fuel can then pass through the combustion chamber into the exhaust system, which can wreak further havoc on the catalytic converter.

3. Fouled Spark Plugs

Fouled Spark Plugs

Water and other ingredients in toothpaste that make it to the spark plugs can foul the tips. This, too, can cause misfires and timing issues, which can leave excess fuel deposits in the catalytic converter and other parts of the exhaust system. If you’re lucky, it will only foul the plugs enough that they can be removed and cleaned. Otherwise, they’ll need to be replaced.

4. Contaminated Oil

Contaminated Oil

The micro-abrasives and other ingredients can easily make their way into the oil via the cylinders. At that point, the particles will be too fine for the oil filter to capture and retain them. Instead, they’ll continue to cycle, growing greater and greater in concentration in every facet of the engine’s oil system.

5. Friction to the Cylinder Walls

Friction to the Cylinder Walls

When micro abrasives from toothpaste enter the cylinders, they work against the lubricating properties of the oil. Not only does this cause more friction from metal-on-metal contact between the pistons and the cylinder walls, but the micro-abrasives themselves can potentially cause long-term scoring. Left unchecked, it could even cause minor compression issues.

6. Crankshaft & Piston Damage

Crankshaft & Piston Damage

Toothpaste has a small amount of water in it. If you were to add a lot, the presence of incompressible water could cause damage to the crankshaft and pistons. However, this is an overkill scenario where someone would put multiple tubes into the gas tank or the combustion chamber.

The Cost to Fix Toothpaste in a Gas Tank

The cost to fix toothpaste in your gas tank will vary depending on how soon you caught it and just how far it was able to make it through the fuel system and engine.

Draining and flushing the Gas Tank

Let’s say that someone else put toothpaste in your gas tank as a prank, and you caught it before starting the car and moving it. In a scenario like this, you might get away with having a mechanic flush the tank, which might only cost you $100 to $150.

Replacing the Fuel Filter

How To: Replace Your Vehicle's Fuel Filter

If you started the car and ran it at all with toothpaste in the gas tank, the wise move is to replace the fuel filter. If you’re a capable DIY mechanic, you can probably do this independently for a part cost of $25 to $55.

Dealing with a Clogged Fuel Pump & Fuel System Cleaning

The humectant ingredients in toothpaste, like sorbitol and glycerol, can congeal to act a lot like tank varnish, which can clog the fuel pump. A professional mechanic might be able to remove the fuel pump and clean it as well as perform a complete fuel system purge & clean.

This could cost you upward of $150 to $200 to have a mechanic do it right the first time.

Though depending on the age of the pump and how strained it was when running clogged, the more reasonable route might be to replace the fuel pump completely. This is something only a mechanic should do. You can expect the final parts and labor cost to run you around $350 to $500.

Check out this video, if you need assistance cleaning your fuel system properly.

Dealing with Clogged Fuel Injectors

🛁 How to Clean fuel Injectors YOURSELF | Cheap 💰 & Easy DIY 👍

A minor case of clogged fuel injectors from long-term fuel system deposits can be dealt with by using a fuel injector cleaner additive. However, this runs the risk of blowing the toothpaste components into the cylinders, further fouling the oil and causing other issues.

So, the wise move is to take the fuel injectors out to clean them manually.

Having a mechanic clean partially clogged fuel injectors ranges from around $75 to $125. However, with the right tools and a little know-how, you might be able to clean your own clogged fuel injectors for under $20. Though you’ll need a fuel injector cleaning tool kit, which can cost between $35 to $125.

If toothpaste has severely fouled the fuel injectors, they might need to be replaced.


If you have a mechanic replace the toothpaste-fouled fuel injectors, you can expect the minimum cost to be around $300 to as much as $650.

Dealing with Contaminated Oil

How to Change Your Oil (COMPLETE Guide)

Contaminated oil and oil sludge from something like toothpaste getting from the gas tank to the engine’s oil system will at least require purging the engine oil and replacing it. If you’re a capable DIY mechanic, you might be able to do this yourself with a basic engine flush using sludge remover followed by a high-quality oil change.

This will cost you less than $100 and will eat the better part of your Saturday afternoon.

If the toothpaste damaged your oil pump, it might need to be replaced. The part cost will run you between $50 to $175. Though it’s usually beyond what a DIY mechanic can handle.

A mechanic replacing the oil pump will add another $175 to $300 to a final repair bill between $225 and $500. Certainly, some foreign models might have higher part and labor costs.

Why Someone Would Put Toothpaste in a Gas Tank

We’ve all been tricked by an internet meme or two, and the prevalence of the “Toothpaste in the gas Tank” hack means it’s bound to trick one or two unsuspecting people. However, there are other ways in which oral care items can make their way into a gas tank.

Vehicle Tampering

For some pranksters, toothpaste in a gas tank is a step up from the old potato or banana in the tailpipe. It could also be done as a form of vandalism.

The problem here is that the victim might not be aware of the problem. I mean, how many of us really smell the nozzle of our fuel filler flap for minty freshness?

You might start your car and drive down the road a way before you notice signs of toothpaste clogging the fuel filter and causing the engine to struggle due to poor fuel system performance.

Criminal Consequences of Vehicle Tampering

Vehicle tampering is a crime with varying punishments based on state laws. However, the minimum penalty is usually a $1,000 fine, plus having to pay the cost to repair the other person’s vehicle.

In some states, if vehicle tampering causes personal injury or damage to another person’s property, from something like the stalling car crashing into a fence or a light pole, the prankster could face a sentence of up to 90 days in jail.

Ways to Improve Your MPG

10 tips that will improve your car's fuel economy for free

Rather than giving in to the evils of internet memes that give you bad advice, there are a few simple things you can do to help maximize your car’s MPG without adding minty freshness to your fuel tank.

1. Change the Oil on Time

Changing your oil on time gives your engine’s moving parts the best advantage for moving smoothly and efficiently. Springing the extra money to get a good oil change with synthetic oil and perhaps adding oil treatment for a high-mileage engine is a smart return on investment.

2. Replace the Air Filter

Replacing your air filter on schedule also helps optimize your miles to the gallon. It ensures that the intake manifold is getting exactly the amount of clean air it needs. This helps ECU to properly balance the fuel/air mixture for optimal internal combustion.

3. Maintain Proper Tire Pressure

If your tires are over-inflated or under-inflated, it will affect their relationship with the road, hampering your MPG. It’s best to check the pressure in your tires at least once a month, even if your car has a tire pressure monitoring system. You should also make sure to check them before a long drive.

4. Try to Avoid Idling

Idling or getting stuck in stop-and-go traffic will also eat into your MPG. Trying to choose wise routes that have as few pointless stops as possible. If your commute does require you to go through rush hour traffic, try to leave a little earlier or later to avoid the worst of the stop-and-go traffic.

5. Don’t Speed

Once you start going over 50 to 55 miles per hour, your fuel efficiency starts to drop rapidly. The more you speed, the more inefficient your engine performance will be. By driving a modest, steady pace, you’ll end up saving a lot more fuel than squirting a tube of minty fresh toothpaste in your gas tank.


Putting toothpaste in your gas tank won’t help your MPG and is more likely to cause you more expensive problems in the future. The most likely thing it will do is clog your fuel filter, which will hamper the fuel pump’s ability to deliver a steady stream to the fuel rail.

If the toothpaste does make it past the fuel rail to the fuel injectors, you have a whole new batch of problems to deal with. Not the least of which being clogged fuel injectors, which can leave unburned fuel in the cylinders, leading to misfires. This can then damage the exhaust system and the catalytic converter.

The micro-abrasives in the toothpaste can also make it into oil, contaminating it. This can increase the friction between the pistons and the cylinder walls, causing severe damage.

If you’re considering putting toothpaste in someone’s gas tank as a prank, you might think twice. Vehicle tampering is a serious crime with stiff penalties. Not only do you eat a $1,000 to $3,000 fine, but you will be held liable for the car’s repair cost. If someone is hurt or property is damaged due to your toothpaste in the gas tank prank, you could face up to 90 days in jail or worse.

No matter how you look at it, putting toothpaste in a gas tank is never a good idea.

Jason Farrell

Written By

Jason Farrell

Jason Farrell is a certified master technician, the editor of Mechanic’s Diary in Pittsburgh, Pennsylvania. He is ASE (Automotive Service Excellence) certified and earned a Bachelor’s Degree in Automotive Technology from Pittsburg State University. With nearly 18 prior years of experience in the automotive field, he has extensive knowledge about Domestic, European, and other foreign makes and models of cars and light trucks. Jason’s experience working as a technician and service manager at dealerships, gave him the experience and know-how of most aspects of inspection, diagnosis, and repair from engine and drivability to electrical, HVAC, brakes, steering and suspension and everything in between.

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