Can You Put WD40 in Gas Tank – Know the Pros and Cons

WD40, a petroleum-based solvent, comes with enormous uses. While its primary function, according to the manufacturer, was to help displace water from objects, invariably preventing rust, it now offers other benefits. And the prominent benefit to name is the removal of rust, grime, gunk, and other impurities from objects.

However, some car enthusiasts advocate using it in fuel tanks to rid water and other contaminants from fuel tanks and even boost fuel economy. While not directly recommended for use in gas tanks by its manufacturer, people are wondering if they could use WD40 in gas tanks.

wd40 in gas tank to save gas

Can you put WD40 in your gas tank?

The primary function of the WD-40 was to displace water from objects. By spraying it on wet objects, they become dry in no time. Hence, it serves as an efficient rust-preventative. However, people have started using it to remove rust, grime, gunk, and even grease from objects.

But now, there are rounds of information on the internet about people spraying WD-40 in gas tanks. Thus, berthing the question, can you put WD40 in a gas tank? Yes, you can, especially if you run a multi-gas engine that uses Kerosene. WD-40 consists mainly of Kerosene and other additives.

While you may also use it for regular gas and diesel engines, it may cause your engine to run poorly. It is, however, worse in gasoline engines. In some cases, gasoline engines may even refuse to start. While WD-40 in a diesel fuel tank will not let diesel engines run to optimal performance.

But why put WD-40 in the gas tank anyway? According to some, it helps in eliminating water and other condiments from the gas tank, that is, making the tank clean. Others also opined that putting WD-40 in gas tanks helps in improving fuel economy.

Read Also: Oil in Gas Tank May be a Mistake, Need, or Hostile Act – What to Do

spraying wd40 in gas tank

What happens if you put WD40 in the gas tank?

While WD40 was never recommended for use in gas tanks, people still use it anyway. According to some, it helps in cleaning the gas tank. For others, it helps improve gas mileage. However, if you’re spraying WD-40 in gas tank to save gas, you would need a lot, like a whole gallon in gas tank. But unfortunately, it will cause you extra expenses. Here is what happens;

WD-40 contains hydrocarbons. So while it will burn, your engine will not process it as fuel since it’s not gasoline. Instead, it will process it as a pollutant in fuel. Hence creating a lot of carbon deposits in the combustion chamber and exhaust system and damage to the catalytic converter.

The carbon deposits in the system will be apparent in the exhaust pipe. As you would witness a lot of exhaust fumes coming off the vehicle. Project farm, a YouTuber, did this experiment to answer those asking if one could use WD-40 in an internal combustion engine or as oil in a crankcase.

According to the experiment, while you can use it, it will result in air pollution as there will be a noticeable increase in exhaust fumes. And while you may be able to save a lot of gas, it will cost you hundreds of dollars in repairs in the future.

Moreover, your vehicle will also not run to its optimal performance, especially for diesel engines. Gasoline engines, in some cases, won’t even start. But the trick is, while it is not recommended for use in fuel tanks, it will take a lot for it to cause harm to your car. That is, using it in large amounts or regularly.

So if at all you use it, use only a tiny amount and make sure you top it with gasoline to the brim afterward before driving. But should you spray WD-40 in the gas tank? While you can, it doesn’t mean you should. It’s better safe than sorry.

Will WD-40 help fuel consumption?

Yes. Many people put WD-40 in gas tanks to save gas. However, there is a price that comes with it. To save fuel, you need WD-40 in large quantities, like up to a gallon in your gas tank, meaning WD-40 will automatically serve as fuel. However, in reality, WD-40 is not fuel, so the engine won’t process it as such.

Instead, the engine will process it as a pollutant, eventually leaving lots of carbon deposits in the combustion chamber and exhaust system. So you will see a high amount of fumes leaving the exhaust. Too much waste in your combustion chamber, caused by water leaving through the exhaust system, may also damage the catalytic converter.

Therefore, while putting WD-40 in a gas tank helps in saving gas, you’re unknowingly preparing for expensive future repairs. So technically, use of WD-40 in large quantities to save fuel will harm your car over time. If you use it in small amounts, it may not harm your engine, but it won’t do the trick either.

Is WD-40 safe on car engines?

WD40 is safe on car engines, especially when used on the engine’s exterior. They are good at removing grease and grime from engine components. They can also help in preventing engines from rusting. The downside is WD-40 is an oil-based solvent.

So, after drying out, it leaves a sticky residue on your engine, eventually attracting dust over time. Again, while it’s fast in removing rust, it soon leaves the surface to rust quickly. So, it’s advisable always to use a degreaser afterward or regularly use the WD40 for rust removal.

The main problem, however, with using WD-40 in car engines is if used in the engine block as oil or mixed with oil. If used on the block instead of the standard engine oil, the engine will process it as a pollutant and cause too much exhaust fumes from the tailpipe. This could even damage your catalytic converter.

Pros and cons of putting WD40 in the gas tank

While WD-40 comes with enormous benefits, it also has its drawbacks. Let’s look at the major pros and cons of putting WD-40 in fuel tank or engine.


  • Serves as a rust inhibitor
  • Prevents corrosion
  • Eliminate grease or gunk from surfaces or objects
  • Helps displace water or moisture from engine components
  • It can be used to improve gas mileage


  • Reduces car performance
  • Causes air pollution due to a drastic increase in exhaust fumes resulting from excess carbon deposits
  • Can damage the catalytic converter, leading to expensive repairs
  • Can damaged objects with plastic or rubber material
  • It can make your engine dirty quickly as it easily attracts dirt and dust after drying out.

Read Also: How to Fix Water In Gas Tank? Symptoms and Effects

Will a Gas Engine Run on WD-40? YouTube

Some FAQs

What happens when you put WD-40 in your engine?

Putting WD-40 on your engine can make a mess of the engine. If you intend to clean the engine, use an engine cleaner instead, accompanied by a rag and a large brush. While WD-40 will help clean the engine, it will leave a sticky residue in your engine after drying out, which eventually attracts dust and dirt, shortening the effect of the clean-up. This can also reduce the overall efficiency of your engine and its components. Again, if you’re using it as a rust inhibitor, it will quickly remove rust from the engine surface. To your dismay, it leaves the surface to rust again quickly because it has low lubricating properties.

Therefore, unless you keep using the solvent frequently or lubricate the engine part after using WD-40 to degrade rust, don’t use it at all. While it has several lubricating properties, it doesn’t lubricate the surface after it dries off, leaving it vulnerable to more rust.

Is it OK to spray WD-40 on a car engine?

It is ok if you’re spraying it on the engine’s exterior. WD-40 helps in removing corrosion and rust, penetrates gummed components, removes grease and moisture, and also serves as a mini lubricant. So, it can be used to care for engine covers.  If you’re using it as a cleaner, it’s a good bet as it easily cuts through grease and grime that accumulate around engine parts.

However, when it dries off, it will leave a sticky residue, which later attracts dirt. Again, it also helps in preventing and eliminating rust from engine parts. If, however, you don’t use a degreaser afterward or regularly use the WD-40, the dust surface will be left to rust again.

WD-40 can also eliminate carbon deposits and displace water from spark plugs and its wires. Yes, WD means water displacement. So, if you have wet or dirty spark plugs or need to remove moisture from the ignition system, then WD-40 can be sprayed in the engine. So, if you’re asking why would you put WD-40 in your engine? Now you know.

Does WD-40 damage cars?

Yes, WD-40 can damage your car if used in a gas tank as fuel or oil in the crankcase. This brings us to ask, is it ok to put WD-40 in gas tank? Generally, it’s not recommended to be used in gas tanks, But people will always go the extra mile. According to some car enthusiasts, putting WD-40 in gas tank helps save gas and is sometimes used as oil in the crankcase.

While a little quantity in the gas tank won’t harm your car, it can’t help you save gas. Therefore, to save gas, you need a large amount of WD-40 in your gas tank. And this is where the problem sets in. WD-40 contains hydrocarbons, and it’s not fuel. So while it might burn, the engine won’t process it as fuel but as a pollutant.

This causes large amounts of carbon deposits in the combustion chamber and the intake and exhaust valves, which invariably damages the catalytic converter. Damaging your catalytic converter is synonymous to damaging your car. The situation is the same whether used in a gas tank or as oil in the crankcase.

What should you not put WD-40 on?

There are many things never to Put WD-40 on, but here are a few. Don’t use WD40 on door hinges. While it will stop the squeaks, it will later attract rust and dirt, leaving you with uglier dark door hinges. Avoid using WD40 on bike chains as they leave a sticky residue, which eventually attracts dust; use bike lubricants instead.

Also, don’t use WD40 on locks as they can damage the internal components; graphite powder should do the trick here. Avoid using WD40 on any plastic or rubber components, as it can dry them out and damage them. It should not be used on bearings as it may dilute the grease and damage the bearings.

You should also not use it in areas that need a long-term or continual lubrication; that area will get rusty again in no time. More importantly, don’t use it on your skin. It contains a Neurotoxin that penetrates into the blood quickly upon contact. It will eventually damage your heart and kill you. It sounds crazy, but people do spray it on their knees and elbows to rid of arthritis.

What can I put in my gas tank to save gas?

Buying gas is expensive, especially when you drive a lot. So many drivers are looking for means to limit gas consumption and save money. However, while people put WD-40 in gas tanks to save gas, it comes with its pitfall, which is future expensive repairs. So, what can I put in my gas tank to save gas?

For those who rarely drive or are taking their cars for storage, you can add fuel additives like fuel stabilizers to the gas tank so the gas doesn’t go bad. So instead of flushing out the gas and cleaning the carburetor before use, you can drive it immediately. The gas will remain as it has been the time you stopped driving your car.

Read Also: What Happens If You Put Sugar In Gas Tank?

Final Words

Putting WD-40 in gas tank comes with its advantages and drawbacks. While it’s not recommended for use in gas tanks, many do use it anyway, as a small amount won’t harm the engine. The problem sets in when people try to use it as a gas-saving mechanism. To save gas, you need a large amount of WD-40 in your gas tank.

However, the engine doesn’t recognize it as fuel and won’t process it as one but as a pollutant instead. But doing so leaves excess carbon deposits in the combustion chamber and exhaust system that eventually damage the catalytic converter. While it comes in handy in saving gas, it can also incur future expenses. It will also cause your vehicle to run poorly with a drastic increase in exhaust gases.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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