How to Clean a Catalytic Converter With Seafoam? – 2 Methods

Written by

Bruce Sonnier


Marcus Dutton

how to clean a catalytic converter with seafoam

The internet is flooded with information about cleaning catalytic converters in cars, which may confuse people in determining what’s reliable and what’s not.

Despite the many claims online on how to clean a clogged catalytic converter, you should find which ones provide the right solutions, to avoid ending up with expensive repairs.

Here are some effective methods on how to clean a catalytic converter with Seafoam with an over-the-counter treatment solution.

Ways to Clean a Cat Converter With Seafoam

Catalytic converters play a crucial role in cars that serve as a vital emissions control unit, where it converts toxic pollutants into safe gases before it exits the exhaust pipe.

However, catalytic converters need to stay clean for them to function properly.

Enter Seafoam, a water treatment liquid additive that doubles as a cleaner for fuel lines and engines. It is made primarily of petroleum products, which include isopropyl alcohol and kerosene.

What to prepare

There are basically two ways of using Seafoam as a catalytic converter treatment solution.

Although Seafoam is not specifically formulated as a catalytic converter treatment formula, it can be used as a fuel additive or oil additive method.

It is not a standalone catalytic converter cleaner spray but is most effective when combined as an additive to prevent cat converters from clogging up.

Method 1: As a fuel additive catalytic converter cleaner

The best way to use Seafoam to help clean or detoxify your catalytic converter is to use it together with the fuel that gets distributed throughout the engine and cat converter before safe gases are expelled at the exhaust.

As a fuel additive, it lubricates and cleans the fuel passageways throughout the combustion chamber, upper cylinders, intake valves, and carburetors, which helps maintain the efficient function of your car’s converter.

What you need:

  • Seafoam motor treatment
  • Funnel
  • Rags or old towels

Step 1: Mix the seafoam in the right amount

There are two ways this can be added to your fuel.

With the engine off, 1) you could do this while re-fuelling at a gas station or 2) at home in a well-ventilated area.

  • Open the gas cap, use a funnel, and pour in based on the ideal ratio of 1 ounce of Seafoam for every gallon of gasoline.

Step 2: Warm it up


Turn on the engine and let it run on idle for a few minutes to allow the additive to circulate thoroughly inside the engine and cat converter.

Step 3: Pour the sea foam into the tank


For cars with carburetors, set aside 1 part of Sea Foam to 4 parts of gasoline that are in your tank.

Step 4: Start the engine

Start the engine then leave it on idle for around 8 minutes to allow the additive to work its way through the carburetor passages and circuits, then turn the engine off. Wipe off excess liquids in the work area using the rags.

Step 5: Leave it overnight

Leave the engine off overnight for up to three days to allow the additive to do its cleaning job.

Step 6: Turn the engine on again

Turn on the engine then run on idle for another five to ten minutes to re-circulate the additive during the rest period. After which, you can operate your vehicle normally. The higher the engine compression, the better the cleaning power.

Method 2: As an oil additive catalytic converter cleaner

When using Seafoam without removing the cat converter, mix it as you would any oil additive that you combine with your engine oil with a ratio of one ounce per quart of oil.

What you need:

  • Seafoam motor treatment
  • hand gloves
  • safety glasses
  • funnel
  • old towels or rags
  • solvent degreaser

Step 1: Take precaution

Ensure that your car is parked in a well-ventilated area with the engine turned off and cool before you start using Seafoam for a catalytic converter.

Also, take the necessary safety precautions, such as wearing your safety glasses and gloves before starting the process.

Step 2: Apply solvent degreaser


Make sure that the engine and surrounding areas are clean of any debris or liquids such as oil residue.

The easiest way to do this is to use a solvent degreaser on engine surfaces with oil to avoid contaminating the Seafoam cleaner when it is poured into the engine.

Step 3: Pour the right amount of seafoam cleaner


Remove the cap of your engine oil reservoir and use a funnel to carefully pour in the Seafoam cleaner. Replace the oil crankcase cap when done and ensure it is secured after using the Seafoam catalytic converter cleaner.

Step 4: Turn on the engine


Turn on your car engine and let it run for a few minutes so the Seafoam additive gets distributed properly throughout the engine and the combusted fuel gas moves onto the catalytic converter. This process initiates cleaning of the exhaust system.

Step 5: Turn off the engine

After several minutes, turn off the engine until it cools down. Once the engine has cooled, use the old towels or rags to clean and remove any Seafoam residue from the outer oil crankcase.

Do remember, though, that as mentioned before Seafoam alone will not clean the catalytic converter, more so when it is severely clogged or nearing its end of life.

What it does, however, is help prolong the life of the car’s catalytic converters by ensuring all the engine networks, fuel pipes, and combustion chambers are clean and free from residue to ensure cat converters function properly and perform optimally.

Is There a Better Alternative to Help Clean or Detoxify the Catalytic Converter Directly?


There are brands in the market that are used to directly clean cat converters and are prescribed specifically for use as a catalytic converter cleaner.

One of the most popular brands is Cataclean, which is used as an engine and fuel detoxification treatment solution to clean catalytic converters.

There’s not much difference between Cataclean vs Seafoam, since both solutions are introduced into the car’s engine and exhaust system by adding it as a fuel or oil additive.

However, what makes Cataclean stand out is that it is advertised as an additive specially formulated to prevent the fouling of catalytic converters.

What Are the Benefits of Using Seafoam to Clean Catalytic Converters?


As a foul and oil additive, there are numerous benefits to using Seafoam for cat converters.

  • It enhances the lubrication of upper and top cylinder assemblies.
  • It helps stabilize diesel and gasoline fuel for up to two years.
  • It cleans and takes out deposits in the intake valve channels and chambers.
  • It cleans and clears the carburetor and fuel injector passages.
  • When combined with engine oil, it liquefies residues and deposits that are easily ejected through the exhaust system.



Is Seafoam safe for catalytic converters?

Yes and no. Yes, if the engine has been treated with Seafoam regularly as part of a car’s periodic maintenance service.

It’s a no when trying to use Seafoam on catalytic converters that are severely damaged or nearing end-of-life use.

How long does it take for a catalytic converter cleaner to work?

The answer depends on how much and how severely the converters are clogged with residue and deposits, which can take days or even months to get it to do its work properly.

For best results, catalytic converter cleaners are more effective when it is used regularly as part of a vehicle’s regular maintenance service such as engine oil change, or for every 3000 miles of travel as a fuel additive.

It helps eliminate deposits and buildup inside the engine, by breaking it down and liquefying it to allow it to pass cleanly through the cat converter without clogging it.

Should I get rid of a catalytic converter?

When a cat converter is faulty, damaged, or no longer functioning properly despite several attempts to clean it, then it needs to be replaced.

Make sure it is properly disposed of by an authorized service technician as it may contain toxic substances that accumulated in it through years of use and abuse.

What are the signs of a bad catalytic converter?

A clogged or damaged catalytic converter creates exhaust backpressure and may show tell-tale signs that it needs replacement.

Symptoms range from a check engine signal in the dashboard oftentimes a P0420 error code, poor engine performance, car unable to start, and failure to pass a routine emissions test.


Catalytic converters play a major role in the life of a vehicle and help ensure the safety of people from toxic emissions when operating a car.

Ensuring that getting your exhaust system is OK can be as simple as knowing how to clean a catalytic converter with Seafoam, prolong the life of your car, and guarantee you more years to enjoy comfort and freedom to travel wherever the road may take you.

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