What Rislone CAT Complete Is

Rislone CAT Complete is a fuel system cleaner designed to remove carbon deposits from your engine's catalytic converter, fuel injectors, and intake valves. It comes as a liquid additive that you pour into your fuel tank, and it works as you drive by breaking down buildup that accumulates over time.

The product is made by Rislone, a company owned by Chevron that produces engine and fuel additives. CAT Complete specifically targets the catalytic converter — the emissions control device that converts harmful gases into less harmful ones — which is why "CAT" appears in the name. The cleaner is sold at auto parts stores and online retailers, typically in a 16-ounce bottle that treats one full tank of fuel.

Unlike some fuel additives that claim to do everything, Rislone CAT Complete has a narrower purpose: it aims to restore catalytic converter efficiency and reduce emissions-related trouble codes. It does not change your oil, protect your transmission, or extend engine life on its own.

Key Takeaways

  • Rislone CAT Complete is a fuel additive that cleans carbon deposits from your catalytic converter, fuel injectors, and intake valves as you drive.
  • One bottle treats approximately one tank of fuel and costs between $8 and $15 depending on where you buy it.
  • The product is designed to help reduce emissions trouble codes (P0420, P0430) and improve fuel economy in vehicles with carbon buildup.
  • Results typically appear after 100 to 200 miles of driving, though some vehicles may take longer depending on how much buildup is present.
  • Rislone CAT Complete is safe to use in all gasoline engines and does not require draining or special procedures.

How the Cleaner Works Inside Your Engine

When you pour Rislone CAT Complete into your fuel tank, the additive mixes with your gasoline. As the fuel flows through your fuel injectors and into the combustion chamber, the cleaner's active ingredients burn alongside the fuel. This combustion process releases compounds that dissolve and break apart carbon deposits that have stuck to your catalytic converter's internal surfaces.

The catalytic converter contains a honeycomb-like structure coated with precious metals (platinum, palladium, rhodium) that trigger a chemical reaction to convert carbon monoxide and unburned hydrocarbons into carbon dioxide and water. When carbon builds up on these surfaces, the reaction becomes less efficient, and your engine's computer detects the problem and triggers a check engine light.

Rislone's cleaner works by softening and dislodging this carbon layer so it can be burned off or flushed through the exhaust system. The product does not require you to remove the catalytic converter or take your vehicle to a shop — it works passively as you drive normally.

When to Use Rislone CAT Complete

The most common reason to use this product is when your check engine light comes on with a catalytic converter efficiency code. The two most frequent codes are P0420 (catalyst system efficiency below threshold) and P0430 (catalyst system efficiency below threshold, bank 2). These codes mean your catalytic converter is not converting emissions as well as it should, but they do not necessarily mean the converter is physically damaged.

You should consider using Rislone CAT Complete if your vehicle has higher mileage (typically 80,000 miles or more), you notice reduced fuel economy, or you have been driving mostly short trips or in stop-and-go traffic. These conditions allow carbon to accumulate faster than highway driving does.

You should not use this product if your catalytic converter is physically damaged, rusted through, or rattling inside (which indicates internal breakdown). In those cases, the converter needs replacement, and a fuel additive cannot fix structural damage. If you are unsure whether your converter is damaged or just dirty, a mechanic can inspect it with a borescope or perform a back-pressure test to determine the actual problem.

Dosage, Cost, and How Long It Takes

One 16-ounce bottle of Rislone CAT Complete treats one full tank of fuel. You pour the entire bottle into your fuel tank before filling up with gas, or you can add it to a full tank and then fill up — either order works. The product costs between $8 and $15 per bottle at most auto parts retailers, making it one of the cheaper fuel additives on the market.

You will see results after driving 100 to 200 miles on the treated fuel. Some vehicles show improvement faster, especially if the buildup is light. Heavier carbon deposits may take 200 to 300 miles or even a second treatment to clear completely. After you finish the treated tank, you can refill with regular fuel — the cleaner does not stay in your system permanently.

If your check engine light does not clear after one treatment, you have two options: run a second bottle through another tank of fuel, or have a mechanic scan your vehicle to confirm the code is still present. Sometimes the light takes a drive cycle or two to reset even after the converter has been cleaned.

What Rislone CAT Complete Does Not Do

This product is designed specifically for catalytic converter cleaning and does not address other fuel system problems. It will not unclog a severely restricted fuel filter, fix a faulty oxygen sensor, or repair a damaged mass airflow sensor — all of which can also trigger emissions codes.

Rislone CAT Complete also does not prevent future carbon buildup. Once you have cleaned your converter, you will eventually accumulate deposits again over time, especially if you drive short distances frequently or use low-quality fuel. Using a fuel with detergents (most top-tier brands include them) can slow the process, but it does not stop it entirely.

The product is not a substitute for a proper diagnosis. If your check engine light is on, the underlying cause could be a bad oxygen sensor, a vacuum leak, or a failing catalytic converter that needs replacement. A mechanic's scan tool can read the specific code and help determine whether a fuel additive is the right solution or whether you need a different repair.

Safety and Compatibility

Rislone CAT Complete is safe to use in all gasoline-powered vehicles, including cars, trucks, and SUVs. It is compatible with all fuel types (regular, mid-grade, premium) and does not damage fuel injectors, seals, or engine components. The product has been used for decades and is widely recommended by mechanics and automotive forums.

You should not use this product in diesel engines, as it is formulated for gasoline combustion. Diesel engines have different fuel systems and catalytic converters, and using a gasoline additive in a diesel vehicle could cause problems.

There are no special precautions needed when using Rislone CAT Complete. You do not need to change your driving habits, warm up your engine longer, or avoid certain roads. straightforward pour it in and drive normally. The product will not affect your vehicle's warranty, though some dealers may argue that using aftermarket additives voids coverage — this claim is generally not enforceable under federal law, but it is worth knowing.

Alternatives to Rislone CAT Complete

If you want to explore other options, several competitors make similar catalytic converter cleaners. Chevron Techron Concentrate Plus, Gumout Regane High Mileage, and Redline Fuel System Cleaner all serve the same purpose and cost roughly the same amount. The differences between them are small — they all work by burning off carbon deposits as you drive.

A more aggressive alternative is a professional fuel system cleaning service, which a mechanic can perform at a shop. This involves running a specialized cleaning solution through your fuel system under pressure, which can remove heavier deposits faster than an over-the-counter additive. These services typically cost $100 to $300 and take 30 minutes to an hour. They are worth considering if you have tried a fuel additive and the check engine light returned quickly.

If your catalytic converter is truly clogged or damaged beyond cleaning, replacement is the only permanent fix. Aftermarket converters cost $300 to $800 depending on your vehicle, while OEM (original equipment manufacturer) converters run $800 to $2,000 or more. Some shops offer core exchanges that reduce the cost if you turn in your old converter.

Frequently Asked Questions

Will Rislone CAT Complete clear my check engine light?

It may, if the light is caused by carbon buildup on your catalytic converter and not by a damaged converter, bad sensor, or other mechanical problem. If the code returns within a few weeks after treatment, the underlying issue is likely something other than dirty deposits, and you should have a mechanic diagnose it.

Can I use Rislone CAT Complete in a vehicle with a new catalytic converter?

Yes, it is safe to use, but you probably do not need it. New converters are clean and efficient. Using a fuel additive preventatively in a newer vehicle is optional and depends on your driving habits and fuel quality.

How often should I use Rislone CAT Complete?

Most people use it once or twice a year, or whenever a check engine light appears. There is no harm in using it more often, but it is not necessary for routine maintenance. If you drive mostly short trips or use low-quality fuel, using it once or twice yearly may help prevent buildup.

Does Rislone CAT Complete improve fuel economy?

It may improve fuel economy slightly if your catalytic converter was severely clogged and restricting exhaust flow. A cleaner converter allows your engine to breathe more easily, which can reduce fuel consumption by a small amount. However, do not expect dramatic improvements — most users report 1 to 3 miles per gallon gains at best.

What if I use Rislone CAT Complete and the check engine light stays on?

Have a mechanic scan your vehicle to see if the code is still the same or if a different code has appeared. If the P0420 or P0430 code persists, your converter may be damaged rather than dirty, or another problem (oxygen sensor, vacuum leak) may be causing the light. A second treatment is an option, but professional diagnosis is usually the better choice.