How To Clean a Catalytic Converter With Seafoam? Does It Work?

Catalytic converters play a vital role in reducing harmful emissions from your vehicle. This guide delves into their function, maintenance tips, and common troubleshooting. While Seafoam is a popular fuel system cleaner, it cannot clean catalytic converters. Learn about professional cleaning methods, alternative solutions, and maintaining optimal converter performance for a cleaner and more efficient ride.

Seafoam is a popular fuel additive and engine cleaner claimed to dissolve gum, varnish, carbon deposits, and moisture in petrol and diesel engines. However, Seafoam is not specifically designed to clean catalytic converters. This article provides an in-depth look at Seafoam’s capabilities, limitations, and the viability of using it as a catalytic converter cleaner.

Key Takeaways From Seafoam Cleaner Review

  • Seafoam is not designed for cleaning catalytic converters. It’s primarily intended for cleaning fuel systems and engines.
  • Adding Seafoam to fuel leads to dilution and insufficient concentration to reach the converter and clean deposits.
  • Direct application of Seafoam to the converter is dangerous and can damage its internal components.
  • Professional cleaning services or replacements are recommended for clogged catalytic converters.
  • Seafoam offers various benefits for fuel system cleaning and engine maintenance when used properly.
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Sea Foam SF-16-4PK Motor Treatment Multi-Use Fuel Additive

  • Seafoam is not designed for cleaning catalytic converters
  • Restoring lost power and performance
  • Cleans fuel injectors, valves, pistons, rings, and combustion chambers
  • Removes moisture, gum, varnish, carbon, and other deposits
  • Treats ethanol-related problems like corrosion in petrol engines
  • Extend Engine Life

What is Seafoam and How Does it Work?

Seafoam is a petroleum-based formula marketed as a complete fuel system and engine cleaner. It contains light petroleum distillates, polyether amine, and polyisobutylene compounds.

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When added to fuel, Seafoam works in three ways:

  • As a fuel stabilizer to prevent gum and varnish formation
  • As a moisture controller to remove water from fuel systems
  • It is a carbon cleaner that dissolves and removes deposits from intake valves, injectors, pistons, rings, combustion chambers, and exhaust components.

The polyether amine additives help clean deposits, while the petroleum distillates act as a carrier fluid, allowing deeper penetration into engine components.

Seafoam aims to remove contaminants, improve engine efficiency, increase power, smooth rough idling, and prevent stalling or hesitation issues.

Is Seafoam Safe for Engines?

Seafoam is generally safe for petrol and diesel engines when used as directed. The manufacturer recommends adding it to fuel at a dilution ratio 1:1000, or 3-5 ounces per gallon of fuel. This allows the cleaner to work gradually without shocking the engine.

Seafoam can also be used in concentrated form as an intake valve/combustion chamber cleaner. This involves slowly introducing small amounts of concentrate directly into the intake manifold via the throttle body or carburetor. This allows it to work through the engine over several tank fills.

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Excessive concentrations or improper direct injection of Seafoam into the engine can damage components. It should never be poured directly into the converter. Always follow manufacturer instructions carefully.

Benefits of Using Seafoam

Some key benefits of using Seafoam include:

  • Cleans fuel injectors, valves, pistons, rings, and combustion chambers.
  • Removes moisture, gum, varnish, carbon, and other deposits.
  • Restores lost engine power and smoothness.
  • Improves throttle response and acceleration.
  • It helps stabilize fuel and prevent future deposit buildup.
  • Treats ethanol-related problems like corrosion in petrol engines.
  • It can extend engine life by reducing wear and oil contamination.
  • Comparatively affordable vs. professional fuel system cleaning.

Independent testing has verified Seafoam’s effectiveness in removing intake valve deposits, improving engine performance, and reducing emissions when used regularly.

Proper Usage Directions for Seafoam

Seafoam can be used in three ways, always adhering strictly to manufacturer instructions:

  1. As an additive to fuel: Add 3-5 oz per gallon of petrol or diesel fuel. For ongoing maintenance, treat every 3,000-5,000 miles.
  2. In the crankcase oil: Add 4-6 oz to engine crankcase oil to help clean and lubricate upper cylinder components. Change the oil after 100-200 miles of driving.
  3. As an intake valve/combustion chamber cleaner: Introduce concentrated Seafoam directly into the intake manifold slowly at a rate of 1-3 seconds per ounce using a mechanical or vacuum tool. Reapply every 6-12 months or oil change.

Why Seafoam Cannot Effectively Clean Catalytic Converters

While Sea foam excels as a fuel and engine cleaner, it cannot effectively clean catalytic converters. There are several reasons why:

Inadequate Concentrations Reach the Converter

When mixed in fuel or oil, the Sea foam becomes too diluted to provide meaningful cleaning effects once it reaches the converter. Testing shows that POT (pour-in-the-tank) fuel additives like Seafoam cannot penetrate and remove substrate-embedded deposits with the fuel dilution ratios required for safe engine use.

Location in the Exhaust Prevents Contact

Catalytic converters are located in the exhaust system, downstream from the engine and combustion process. This makes it difficult for cleaners mixed in fuel or oil to ever reach the converter in sufficient concentrations. Minimal cleaner residue may enter the converter through the exhaust valve blow-by or during cold starts before reaching operating temperature, but not enough to provide significant cleaning action.

Inability to Soak and Penetrate Internal Components

Professional-grade catalytic converter cleaners actively soak and penetrate the converter internals to dissolve deposits. Cleaners introduced through fuel lack the concentrated strength and direct contact time needed to break down contaminants and restore catalytic function properly.

Potential Damage from Improper Use

Attempting to inject or pour Seafoam directly into a clogged converter is dangerous. It can severely damage the fragile ceramic honeycomb structure. This voids the converter warranty and necessitates replacement. Always use fuel additives like Seafoam strictly as directed by manufacturer guidelines.

Safer Methods for Cleaning Catalytic Converters

Instead of fuel additives like Seafoam, experts recommend using professional catalytic converter cleaning services or replacement when they become contaminated and lose efficiency.

Professional Cleaning Services

Specialized service shops have high-pressure CO2, ultrasonic, and chemical cleaning systems that flush and remove carbon, oil, and other stubborn deposits without damaging the converter internals. This can often restore converter performance and allow it to pass emissions testing if the catalyst has not been irreversibly damaged.

Common professional cleaning techniques include:

  • Hydrogen Cleaning – Uses hydrogen gas to burn off hydrocarbon deposits and reset the catalytic metals.
  • Ultrasonic Cleaning – Employs high-frequency sound waves in a liquid bath to dislodge contaminants.
  • CO2 Cleaning – Blasts dry ice pellets through the converter to freeze and dislodge stuck soot.
  • Chemical Immersion – Submerges converter in a specially formulated solvent bath to dissolve deposits.

Professional cleaning typically costs $80-$250 and effectively restores the converter function properly.

Catalytic Converter Replacement

When the catalytic converter is too heavily contaminated for cleaning, replacement is required. Replacement restores tailpipe emissions to like-new levels and allows the vehicle to pass emissions testing. OEM or high-quality aftermarket converters should be used to maintain long-term reliability. Prices range from approximately $300 to $2500, including parts and labor.

Selecting an Effective Catalytic Converter Cleaner

What to look for when choosing a catalytic converter cleaner:

  • Explicitly designed for catalytic converter cleaning.
  • It contains active ingredient chemicals like cerium, platinum, or palladium that interact with the converter surface and help loosen deposits.
  • It uses a gradual cleaning approach to avoid damaging the substrate.
  • It can provide preventive maintenance when used regularly.
  • Has good customer reviews and industry reputation.

Effective Uses for Seafoam

While Seafoam cannot clean catalytic converters, it serves many beneficial purposes when used properly:

  • Cleans intake valves, cylinders, injectors, rings, chambers, pistons
  • Removes fuel system gum, varnish, moisture, and residue
  • Stabilizes fuel to prevent future deposit formation
  • De-glaze cylinder walls to improve ring sealing
  • Quiets noisy lifters and high-mileage engines
  • Cleans varnish in petrol fuel systems caused by ethanol
  • Removes soot from diesel engine components
  • Dissolves thick, stale petrol residues in stored equipment

Seafoam is useful for:

  • Preventative engine maintenance in all petrol/diesel vehicles
  • Restoring lost power and performance
  • Reducing oil contamination and engine wear
  • Passing emissions tests (except in severely clogged converters)
  • Fixing poor idling, hesitation, surging, or stalling
  • Improving cold-starting and warm-up performance
  • Cleaning gummed carburetors in classic vehicles
  • Lubricating upper cylinders during oil changes
  • Winterizing outdoor power equipment and small engines

Use Seafoam as directed to clean fuel systems and engines, but avoid attempting to use it as a DIY catalytic converter cleaner. Instead, utilize professional cleaning or replacement when converters require service.

Where to Buy Seafoam

Seafoam is readily available at major auto parts retailers across the United States, Canada, and Australia. Here are some of the popular stores where you can find it:

  • AutoZone
  • O’Reilly Auto Parts
  • Advance Auto Parts
  • Pep Boys
  • NAPA Auto Parts
  • Canadian Tire
  • Repco Australia

It’s also available at major retailers like Walmart, Amazon, grocery and hardware stores that carry automotive chemicals.

Seafoam comes in 10 oz, 16 oz, and 32 oz bottles for topping off fuel tanks during fill-ups. Larger 128 oz and gallon containers are designed to add directly to bulk fuel or for intensive cleaning.

Online purchasing is convenient through retailers like Amazon or the official Seafoam website, which offers multi-pack discounts. Seafoam frequently goes on sale at various retailers, so it pays to compare prices.

Alternatives to Seafoam

Other top fuel injectors and engine cleaners include:

Gumout Multi-System Tune-Up – A petroleum-based formula similar to Seafoam contains fewer additives. Moderately effective for routine maintenance.

STP Fuel Injector Cleaner – contains a PEA-based cleaning agent and lighter mineral spirits for more regular use. It helps restore lost power and fuel economy.

Red Line Complete SI-1 Fuel System Cleaner – highly concentrated synthetic formula with an advanced additive package provides excellent cleaning power. Provides both maintenance and restoration of neglected systems.

Chevron Techron Concentrate Plus – OEM-recommended and TOP TIER-approved cleaner uses patented PEA technology. It is considered very effective but costs more than competitors.

Liqui Moly Jectron Gasoline Fuel Injector Cleaner is a popular German-made cleaner designed to dissolve tough carbon deposits and tar-like residue. Used widely across European brands.

Berryman Chemtool B-12 Fuel System Cleaner – contains strong aromatic solvents and detergent additives to remove stubborn varnish and carbon deposits. Aggressive cleaner is best for older engines.

3M 08812 Fuel System Tune-Up Kit – provides a manual method of cleaning injectors, valves, and chambers by dissolving deposits into the crankcase oil. The kit includes precision attachments.

Cataclean Engine and Catalytic Converter Cleaner – designed to clean CATs and oxygen sensors using ceramic catalyst technology. Works gradually when added to fuel.

ATP AT-205 Reseal Tank Sealant – contains a blend of conditioners and sealants that swell and recondition fuel system gaskets and O-rings. It helps soften and remove deposits while preventing leaks.

Maintaining Catalytic Converter Performance

Here are some tips to help preserve catalytic converter function and efficiency:

  • Keep your vehicle well-maintained with regular tune-ups, oil changes, and engine service. This prevents oil consumption and excess emissions that contaminate the converter.
  • Fix drivability problems immediately, like misfires, leaks, or ignition issues. Continuous misfires dump unburned fuel into the converter, causing overheating and damage.
  • Avoid using leaded petrol where possible. Lead contaminates the catalyst coating on the converter and disables it.
  • Drive smoothly and avoid excessive idling to prevent engine over-fueling. This minimizes converter overheating and carbon buildup.
  • Consider using a fuel cleaner like Cataclean, designed to prevent CAT contamination with regular use. Never use harsh chemical cleaners not intended for catalytic converters.
  • Have your converter regularly inspected and cleaned professionally after 50,000-75,000 miles to prevent irreversible loss of function. Replace it if substrate meltdown is present.

FAQs On Seafoam Cleaner

Can Seafoam Damage Your Engine if Used Improperly?

Yes, using too much Seafoam or pouring it directly into the engine can damage seals, gaskets, sensors, and internal components. Always follow the manufacturer’s instructions carefully.

How Does Seafoam Clean the Combustion Chamber?

When introduced through the intake system, Seafoam helps clean combustion chambers by dissolving carbon deposits, oil residue, and fuel varnish. Its cleaning agents vaporize and are carried into the chambers during operation.

Can Seafoam Use directly On Catalytic Converter as Catalytic Converter Cleaner?

Using Seafoam directly on the catalytic converter is not advised, as it could potentially harm the converter and lead to malfunctions.

Does Seafoam Clean Catalytic Converter?

No, Seafoam doesn’t clean catalytic converters.

Will Using Seafoam Improve Gas Mileage?

Cleaning your engine with Seafoam can help restore lost fuel economy by removing deposits that restrict airflow, reduce compression, and cause your engine to work harder. Just don’t expect dramatic mileage gains.

Can You Pour Seafoam Directly into the Gas Tank?

Yes, Seafoam can be poured directly into the gas tank when refueling. Use 3-5 ounces per gallon of petrol and drive normally until the tank is almost empty to allow it to circulate.

Does Seafoam Have Any Fuel Stabilizers or Conditioners?

Seafoam contains antioxidant additives that help stabilize fuel by preventing varnish and gum formation over long-term storage. It also helps remove moisture.

How Often Should You Use Seafoam in a New Car?

For petrol engines in new cars, consider using Seafoam as preventive maintenance every 5,000 miles or at oil change intervals. Use it more frequently at the first signs of deposits forming.

Can You Use Too Much Seafoam?

Yes, only use the recommended amounts. Excessive concentration can damage sensors, O2 sensors, and the catalytic converter. It could also thin the oil too much.

Does Seafoam Work for Diesel Particulate Filters?

Seafoam helps clean diesel fuel injectors, cylinders, and pistons. However, it cannot directly clean a diesel particulate filter. Professional DPF cleaning is required when it becomes clogged.

How Long Does It Take for Seafoam to Clean an Engine?

Most people report cleaner operation and smoother idling after just 1 treated gas tank. But it takes a few tanks to clean all components fully. Effects are immediate when used in concentrated form.

Can Seafoam Be Used on Motorcycles?

While Seafoam is a viable option for cleaning motorcycle engines, exercise caution if your motorcycle has an oxygen sensor-equipped catalytic converter. In such cases, only use Converter Safe Seafoam to avoid potential damage.

Will Using Seafoam Fix an Exhaust Leak?

No, Seafoam cannot seal or repair exhaust leaks. It can help clean deposits from leaky exhaust components, but the leak must be fixed through exhaust repairs.

Can Seafoam Clean Varnish from Petrol Fuel Systems?

Yes, Seafoam is highly effective at removing varnish, gum, and residues caused by ethanol-blended fuels in petrol engines. It helps clean the full fuel system.

How Does Seafoam Compare to Techron or Red Line Fuel Cleaners?

Seafoam provides effective, complete fuel system cleaning for routine maintenance, while Techron and Red Line offer more powerful catalytic converter cleaning for neglected systems with heavy carbon buildup.

Does Sea foam Have Less Smell Than Other Cleaners?

Seafoam has milder-smelling light petroleum distillate carriers than aggressive solvent-based options like Berryman B12 or Gumout Regane. But it still has a detectable odor during use.

Can You Use Sea Foam in a Lawn Mower or Chainsaw?

Seafoam can help clean gum, varnish, and moisture from small engines like lawnmowers, chainsaws, snow blowers, generators, etc. Follow mix ratios and directions carefully.


Seafoam, while effective for cleaning fuel systems and engines, is not an adequate solution for clogged catalytic converters. In such cases, professional intervention or replacement may be necessary.

Adding it to fuel results in over-dilution, making reaching the converter in concentrations strong enough to dissolve stubborn deposits impossible. Attempting improper direct application to the converter also risks damaging the fragile ceramic honeycomb matrix.

For optimal emissions control performance, professional cleaning services or replacements are strongly recommended when catalytic converters require servicing due to clogging. Still, Seafoam has many benefits as part of a regular fuel and engine maintenance program to clean intake components and prevent future deposit buildup when used properly.

I am Nicolas, an automobile engineer with over 5 years of experience in exhaust systems and catalytic converters. I am passionate about learning and understanding how things work, and I am always looking for new ways to improve the performance and efficiency of automotive exhaust systems. Know more about me. As an Amazon Associate, we earn commission from qualifying purchases.

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