How To Use Catalytic Converter Additive?

As an ASE-certified master technician who has diagnosed countless catalytic converter-related issues, vehicle owners often ask me about using aftermarket chemical additives. These specialized formulations claim to clean out contaminated converters, restore lost performance and efficiency, and reduce harmful tailpipe emissions. When applied correctly, the suitable high-quality catalytic converter additive can help extend the working lifespan of an aging converter and avoid the high replacement cost. However, misuse of additives carries serious risks, and they should only be viewed as temporary remedies, not permanent cure-all fixes.

In this extensive guide, I’ll cover everything you need to know about properly using catalytic converter additives as a vehicle owner. From understanding exactly how they work to proper and safe application procedures to evaluating their effectiveness, you’ll have a comprehensive understanding of maximizing these converter care chemicals while avoiding the pitfalls. Let’s get started.

What is a Catalytic Converter, and How Does it Work? 

First, a quick primer on what a catalytic converter is and how this ingeniously designed device utilizes specialized catalysts to scrub pollutants from exhaust: 

A catalytic converter is a vital emissions control device on all modern gasoline-powered vehicles. It comprises a stainless steel outer shell containing a fragile honeycomb structured ceramic brick coated with precious metal catalysts.

The most common catalytic converter catalysts used are platinum, palladium, and rhodium. As the hot exhaust gases exit the engine and pass through the converter containing these catalysts, a chemical reaction occurs that converts harmful pollutants like carbon monoxide into far less toxic compounds. 

For example, the specialized catalysts facilitate reactions that break down dangerous carbon monoxide into carbon dioxide and convert hydrocarbons and nitrogen oxides into simple water and nitrogen gas. When emitted from the tailpipe, these altered compounds are much less toxic to the environment.

Extensive emissions testing conducted by the Environmental Protection Agency has proven that today’s high-tech catalytic converters can eliminate over 90% of three major toxic tailpipe pollutants – hydrocarbons, carbon monoxide, and various nitrogen oxides. This enables vehicles to comply with emissions regulations under the Clean Air Act, drastically reducing the amount of air pollution emitted from the exhaust.

However, over extended time and accumulated mileage, the performance and effectiveness of a catalytic converter will gradually decline. Contamination from oil or fuel additives getting inside the converter, temperature damage to the fragile substrate, and everyday wear will degrade function over the years. Adding specialty aftermarket catalyst fortifying additives can help restore lost performance and keep your converter running more efficiently.

When Should You Consider Using a Catalytic Converter Additive?  

Suppose you are noticing any of the following symptoms. In that case, it likely indicates that your catalytic converter may be fouled, restricted, or losing conversion efficiency. In these cases, treatment with a dedicated catalyst additive can help clear out deposits and restore proper operation:

  • Noticeable decrease in engine performance and gas mileage
  • Failure of a state emissions or smog test that was previously passed 
  • Fouled or blackened spark plugs within a short time after being changed
  • A strong rotten egg smell is frequently present in the exhaust 
  • Visible smoke emitting from the exhaust pipe
  • The check engine light comes on with diagnostic trouble codes pointing to the catalytic converter

Preventively treating your catalytic converter with additives can help maintain a healthy, fully functioning system. I recommend additive application during routine oil changes or approximately every 30,000 miles of usage as regular maintenance for most vehicles.

Whenever you notice a concerning dip in engine performance or gas mileage that you suspect may be related to declining catalytic converter functionality, re-apply an additive treatment within the following couple of fuel tanks. 

It’s also wise to preventively treat your converter with additives after installing a new OEM or aftermarket replacement converter. This helps ensure the fresh catalyst maintains optimal function by keeping surfaces clear of initial contaminants.

Choosing the Right Catalytic Converter Additive for Your Vehicle

With the sheer number of catalytic converter cleaner products and brands available these days all touting impressive results, choosing an effective additive treatment suited for your particular vehicle and engine can be confusing. 

Here are some expert tips for selecting the optimal catalyst restorative additive:

  1. Where possible, match the dedicated additive product you select to the specific size range of your vehicle’s engine. Many formulas are designed for small, medium, large, or full-size engines.
  2. Closely compare active ingredient lists and concentrations. Quality brand name additives often contain generous amounts of platinum, cerium, magnesium, or other compounds specifically engineered to restore catalytic function. Avoid older silicone-based additives that can foul oxygen sensors.
  3. Research product reviews, forum feedback, and user ratings across multiple brand options. Look for consistent satisfaction and reports of tangible results like passing emissions tests, MPG boosts, etc.  
  4. Stick with a reputable, well-known additive manufacturer. Companies like Wynn’s, 3M, Lucas, Red Line, and BlueDevil invest far more in research and development. Avoid untested, no-name generic brands that may be ineffective.

Proper Application Steps for Using Catalytic Converter Additive

Once you’ve selected an appropriate and high-quality catalytic converter restorative additive for your specific vehicle, carefully follow these steps for safe and effective treatment:

  1. Park your vehicle on a flat, level surface in a well-ventilated area and run the engine for a minimum of 5 minutes to warm it up to normal operating temperature. Shut off once fully warmed up.
  2. Locate the catalytic converter inlet pipe, often found on either side of the engine firewall closest to the driver or passenger seat footwell.  
  3. Thoroughly clean any dirt, grease, or debris buildup from the area surrounding the converter’s inlet pipe opening so it does not obstruct additive flow.
  4. Vigorously shake the container of additive to mix contents thoroughly. Attach the included applicator tube if required. 
  5. Re-start the vehicle’s engine and leave it running. Empty the entire contents of the additive container into the converter’s inlet pipe with the engine running.
  6. Allow the engine to idle for 10-15 minutes with the AC turned off to prevent stalling. This provides adequate time for the total dose of additive to circulate correctly.
  7. Finally, take the vehicle for a short test drive, varying speeds, and running through gears. This ensures full circulation of the additive through the converter to achieve maximum cleaning action.  

Following the manufacturer’s recommended dosage instructions is critical based on your specific engine’s displacement and cylinder count. Overdosing risks plugging the catalytic converter with excess chemicals. Wear gloves and eye protection when handling and pouring the additive as a safety precaution.

How Effective Are Aftermarket Catalytic Converter Additives?

Over the years, there has been considerable third-party testing and analysis on the effectiveness of various aftermarket catalytic converter additive formulas. Overall, the testing consensus is that for mildly contaminated converters just beginning to show small declines in efficiency, catalyst-restoring additive cleaners containing concentrated active ingredients such as platinum, cerium, or magnesium compounds can and do help restore conversion efficiency and reduce emissions to an extent.

However, nearly all testing finds these additives far less effective at removing heavy oil or carbon deposits from the catalyst brick or fully unclogging severely restricted catalytic converters in poor internal condition. While beneficial as a temporary remedy, no additive can fully restore a failing converter to like-new function or match the performance of a new OEM or aftermarket replacement converter.

Regarding real-world results, many users report noticeable improvements in gas mileage, averaging 2-3 MPG after a quality additive treatment and passing emissions or smog tests. Their vehicle was previously failing when the converter was untouched. Some users even claim a modest recovery in engine throttle response or power after treatment. However, actual horsepower or acceleration gains are marginal when objectively testing catalyst additives in controlled environments.

Aftermarket chemical additives are helpful periodic maintenance tools for restoring moderate declines in converter performance. However, they should never be considered a replacement for fully diagnosing and addressing underlying mechanical issues or replacing excessively damaged converters. Think of them as an economical band-aid or reprieve, not a permanent fix-all solution.

Professional Catalytic Converter Cleaning as an Alternative 

Suppose repeated applications of aftermarket chemical additives have failed to fully restore your vehicle’s catalytic converter to proper emissions compliance and peak engine performance. In that case, you may need professional cleaning or “decanting” services to avoid purchasing a completely new OEM or aftermarket catalytic converter unit.

  • Highly specialized proprietary services utilize powerful terpene-based solutions, dry ice blasting methods, high-pressure air/gas injection systems, and even concentrated torch heating to burn away heavy oil and carbon contaminant buildup from the catalyst brick interior.
  • Expect to pay approximately $80 on the very low end up to $250 or more for professional catalytic converter cleaning, depending on the overall level of internal contamination and damage sustained. The highest internal damage cases cost the most to resurrect.
  • Completely internally clogged catalytic converters showing severe matrix damage cannot be revived even by professional cleaning. These scenarios require full converter replacement or decanning, as no chemical or mechanical cleaning can restore function.
  • For older, very high-mileage vehicles in particular, having a professional service deeply clean the factory-equipped catalytic converter rather than replacements can potentially restore emissions compliance and return the car to road-ready condition while avoiding the often $1000+ bill for installing a brand new aftermarket converter unit. However, on most regularly maintained vehicles under 100k miles, periodic use of additives remains a far more economical choice over thoroughly cleaning.

Conclusion on How To Use Catalytic Converter Additive?

In summary, when used correctly at manufacturer-recommended dosage intervals on vehicles just beginning to show early symptoms of declining converter performance and emissions compliance issues, high-quality aftermarket catalytic converter additives can genuinely provide a helpful maintenance boost – restoring lost MPG, maintaining catalyst waste-scrubbing efficiency, preventing damaging buildup, and avoiding emissions-related CELs or test failures down the line. 

It is critical to understand that these chemicals do not replace a thorough diagnosis and addressing of underlying mechanical issues nor replace replacement when converters are excessively fouled internally. Responsible use involves:

  • Combining additives with close attention to warning signs.
  • Trying professional cleaning services for severe contamination.
  • Replacing irreparable converters.

With this complete care regimen, catalytic converters can often last their expected lifespan.

Hopefully, this exhaustive guide has provided an extensive look at carefully incorporating catalytic converter additives into your car maintenance program while avoiding misuse and over-dependence. As always, reach out with any other questions!

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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