Can You Put Gas Treatment in a Full Tank? (Explained)

Can You Put Gas Treatment in a Full Tank?

Gas treatments are important for improved performance of a car and their main purpose is to remove deposit buildup and improve fuel efficiency.

Gasoline overtime tends to leave deposits that can damage a car’s fuel system. Therefore, using the gas treatment is to ensure the deposits are removed. But the question is, can you put gas treatment in a full tank?

You can put gas treatment in a full tank but it’s not advisable. The best time to put gas treatment on a gas tank is when the gas tank is nearly empty. You can add the treatment before filling up your tank.

What is a Gas Treatment?

Gas treatment is liquid substances that improve the quality of gas, prevent the gas from changing form, break up water that might have formed in the tank and also clean carbon deposits from the car.

Gas treatment comes in various forms such as; antifreeze, fuel booster, fuel stabilizer, etc., with each type having various functions.

The usage and application of gas treatment in a car will depend on what you are trying to achieve, for instance, if you are using antifreeze in a car, it prevents freezing by removing water from the gas tank.

New cars may not necessarily need a gas treatment but over time as it gets older there will need to remove the buildup of carbons and also improve performance.

Can you Put Gas Treatment in a Full Tank?

Yes, you can put gas treatment in a full tank however it won’t be fully effective this way. The recommended way of putting the gas treatment in a tank is when it is partially filled then top-up afterward.

When the gas treatment is added to a full gas tank it won’t be fully circulated throughout the fuel and it therefore won’t work as it should.

For more clarity, one may have to check the owner’s manual or consult with an auto mechanic on when to add gas treatment to the car. Recommendations vary from one car model to the other.

How Should you Use Gas Treatment?

The usage of gas treatment varies and depends on the type you are using and also for what purpose, different gas treatment has a different application.

Generally, irrespective of the gas treatment, all gas treatments are better when added before fuel combustion.

It is always better to add gas treatment during fill up instead of when it is full, adding during fill up allows the gas to dilute and mix properly with the fuel. This is also a more effective and efficient way of using gas treatment.

The gas treatment that has been used largely determines how it will be applied, some require that the entire bottle of gas treatment be added to a half-filled gas tank while some others work the best half to half i.e. half gas treatment to the half-filled gas tank.

How Long Does Gas Treatment Take to Work?

Gas treatment starts working within a short time, usually between 5 to 10 miles. It is advisable to drive a car immediately after gas treatment is added, by so doing the treated fuel quickly finds its way inside the engine and starts working.

A car that’s not driven immediately will not work in time because the treated fuel needs combustion to be effective.

Once the fuel has been treated, it is better to allow it to run out before refueling, refueling when it’s half-empty will only stop the cleansing process.

Three Best Gas Treatments in the Market

Here are some of the three best fuel injector cleaners or gas treatments in the market:

STP Gas Treatment

STP gas treatment is one of the many brands of gas treatment out there, it is made of jet fuel and other active ingredients.

It is a cleaning agent that improves a car’s gas quality by removing the build-up of carbon and thereby improving the performance.

STP also works by removing water that could lead to freezing from the gas tank.

STP gas treatment is commonly known for preventing deposit buildup, keeping the fuel intake system clean, and also preventing the fuel line from freezing. It is also known for its compatibility with cap-less gas systems.

Like all other gas treatments, STP is best applied when the fuel is filling up and is best suited for gas engines.

Approximately 6 fl. oz bottle of STP is capable of treating 21 gallons of gasoline while a 12 fl. oz bottle can treat up to 28 gallons of gas.

STP can be added to the gas tank before or after fueling and should be used regularly, as often as the gas tank is filled up.

Lucas Gas Treatment

Lucas gas treatment such as Lucas fuel injector cleaner is made from a blend of oils and additives and is suitable for all gasoline and diesel engines either carbureted or fuel injected.

It is highly recommended for vehicles with leaded fuel as it works without causing harmful emissions. If you easily want to pass your smog test then Lucas gas treatment is what you should use.

Lucas gas treatment increases the engine power by cleaning and lubricating the carburetor and injectors causing a reduction in fuel consumption.

Some of the benefits of Lucas gas treatment are its ability to neutralize the low sulfur problem, increase the miles per gallon, and also increase the life of injectors and pumps.

This product mixes with the fuel immediately therefore, it can be added before or after filling the gas tank. It should be added after every 30,000-40,000 miles or each time the transmission fluid is changed.

The recommended use of Lucas gas treatment is 2-3 ounces for every 10 gallons of gas or diesel and it should be poured inside the gas tank.

It may be added between oil changes or with an oil change. If by mistake the recommended usage is exceeded, no harm will come to the car.

Abro Gas Treatment

Abro gas treatment like other gas treatments improves the fuel economy. It also cleanses the carburetor, and the intake port cleans the intake valve deposits, reduces exhaust emissions, etc. It prevents the fuel system from rusting and improves gas mileage.

The gas tank size will determine the volume of Abro gas treatment to be added. You are expected to add 1% of the treatment to the total volume of a gas tank.

Abro treatment is capable of treating up to 20 gallons of gasoline and should not be used in 2-cycle engines. It is better to add when the engine is idling and warmed up to operating temperature

It can be used in bikes and cars, in order to keep the fuel pump and injectors clean, use Abro gas treatment every 5000km. In the process of assembling, coat engine parts with a 50-50 mixture of Abro gas treatment and engine oil.


Ensure to empty a gas tank filled with treated fuel before refueling, else it will disrupt the whole cleansing process. One effective way of preventing the fuel system from being damaged is by adding gas treatment as often as you can, if possible when changing other oils in the car.