The 20 Minute Japanese Hack to Unclog Your Catalytic Converter

00:00 Hi, my name is Adrian and this is Car

00:02 Care Garage.

00:03 3 months ago a dealership handed me a

00:05 repair quote for $1,200

00:08 >> [music]

00:08 >> and told me my catalytic converter was

00:10 dead.

00:11 I drove home, spent 20 minutes on the

00:13 highway, and watched that check engine

00:15 light turn itself off 2 days later. The

00:17 converter is still working perfectly.

00:20 The dealership never got a single

00:21 dollar. What I used wasn't a magic

00:23 spray, an expensive tool, or some

00:26 sketchy Italian tune-up. It was a

00:28 documented Japanese engineering

00:29 technique that's been quietly saving

00:31 catalytic converters since [music] 1984

00:34 and almost nobody in America talks about

00:36 it.

00:37 What a catalytic converter actually does

00:40 and why yours is slowly [music] dying.

00:43 Let me give you the version of this

00:45 explanation that your high school auto

00:46 shop teacher probably skipped. Your

00:49 catalytic converter sits in the exhaust

00:51 stream between your engine and your

00:53 muffler. Inside that metal shell is a

00:55 ceramic honeycomb structure coated with

00:58 platinum, palladium, and rhodium.

01:00 [music]

01:01 Three precious metals. On a good day,

01:03 that honeycomb structure contains over 1

01:06 million tiny cells, each one coated with

01:09 those metals. [music]

01:11 Each one designed to trigger a chemical

01:12 reaction every single time hot exhaust

01:15 gases pass through. That reaction

01:17 converts three toxic gases into two

01:19 harmless ones.

01:21 Carbon monoxide becomes carbon dioxide.

01:23 >> [music]

01:24 >> Unburned hydrocarbons become water

01:26 vapor. Nitrogen oxides break down into

01:28 plain nitrogen and oxygen. Your car does

01:31 this thousands of times per minute,

01:33 every minute you're driving. The

01:35 catalytic converter is one of the

01:37 hardest working components on your

01:39 entire vehicle and most drivers couldn't

01:42 point to it on a diagram. Here's where

01:44 the dying starts.

01:45 >> [music]

01:45 >> Every engine burns a small amount of

01:47 oil. Every tank of fuel contains trace

01:50 contaminants. Every cold start pushes

01:52 partially combusted fuel through the

01:54 exhaust before the engine reaches

01:56 operating temperature. Over months and

01:58 years, those contaminants don't just

02:00 pass through. They stick. [music]

02:02 Carbon deposits, oil ash, fuel residue,

02:05 and phosphorus compounds from engine oil

02:09 slowly coat those precious metal

02:10 surfaces inside the honeycomb. Cell by

02:13 cell, the converter loses its ability to

02:15 trigger the chemical reaction it was

02:17 built for. This is not sudden failure.

02:20 This is a slow strangulation.

02:22 >> [music]

02:22 >> And here's the part that cost drivers

02:24 thousands of dollars in unnecessary

02:26 repairs every [music] single year.

02:28 A partially clogged catalytic converter

02:31 mimics the symptoms of a dozen other

02:33 problems. Sluggish acceleration that

02:35 feels like a transmission issue. Rough

02:37 idle that gets misdiagnosed as spark

02:39 plugs or fuel injectors. A sulfur smell

02:41 from the exhaust that mechanics blame on

02:44 the fuel system.

02:45 >> [music]

02:45 >> Reduced fuel economy that owners chalk

02:47 up to bad gas or aging engines.

02:50 Meanwhile, the actual problem is a

02:52 honeycomb structure coated in carbon

02:54 that hasn't seen a proper cleaning in

02:56 60,000 mi. And the solution costs

02:59 nothing but 20 minutes of your time.

03:02 The $1,200 lie your mechanic tells you.

03:06 Let me tell you exactly what happened at

03:08 that dealership 3 months ago because

03:10 this conversation happens in service

03:12 bays across America every single day.

03:14 The service advisor plugged in the scan

03:16 tool, read the code, and came back with

03:19 a clipboard. Code P0420.

03:22 Catalyst system efficiency below

03:24 threshold,

03:25 >> [music]

03:25 >> bank one.

03:26 His exact words were, "Your catalytic

03:28 converter has failed. [music] You need a

03:30 new one." Parts and labor, $1,180.

03:34 They'd round it up to $1,200 by the time

03:37 the final quote hit [music] the paper. I

03:39 don't know where that extra $20 went.

03:42 Probably a diagnostic fee for the

03:44 privilege of being given wrong

03:45 information. Here is what that code

03:47 actually means. The oxygen sensor

03:49 downstream of your catalytic converter

03:51 is reporting that the converter isn't

03:53 cleaning exhaust gases efficiently

03:55 enough to meet the threshold programmed

03:57 into your car's computer.

03:59 That is all it means. It does not mean

04:02 the converter is physically broken.

04:04 It does not mean the substrate has

04:05 melted. It does not mean the shell has

04:07 cracked or the honeycomb has collapsed.

04:10 In the majority of cases, especially in

04:12 vehicles under 150,000 mi that haven't

04:16 suffered a serious engine problem, P0420

04:19 means the converter is dirty. The

04:21 precious metal surfaces are [music]

04:22 coated. The chemical reaction is

04:24 suppressed. The downstream oxygen sensor

04:27 is noticing.

04:28 >> [music]

04:28 >> A former dealership service manager in

04:30 Cleveland told Automotive Body Repair

04:32 News, and I'm paraphrasing here, that

04:34 catalytic converter replacements are

04:36 among the highest margin repairs in any

04:38 service department.

04:39 >> [music]

04:40 >> The part costs the dealer between 200

04:42 and $400 wholesale.

04:44 Labor takes 45 minutes to an hour.

04:46 [music] The customer pays over a

04:47 thousand. That math works out

04:49 beautifully for the shop [music] and

04:51 catastrophically for you.

04:53 Here's what makes this worse. Most

04:55 service technicians aren't lying to you

04:57 out of malice. They're working from a

04:59 diagnostic flowchart that says code

05:01 P0420,

05:02 check oxygen sensors. If sensors are

05:04 good, replace catalytic converter. The

05:07 flowchart doesn't have a box that says

05:09 try the Japanese heat cycle method first

05:11 because the flowchart was written by

05:13 people who profit from replacements, not

05:15 from repairs. A mechanic named Gary, who

05:18 runs an independent shop in Ohio and

05:20 asked me not to use his last name, told

05:22 me something I think about every time I

05:24 walk into a service bay.

05:25 >> [music]

05:25 >> He said most clogged cats I see could

05:27 have been saved with a single proper

05:29 highway drive at the right RPM.

05:31 Instead, the customer drove here at 40

05:33 mph on city streets. We plugged in the

05:36 scanner, saw the code, [music] and wrote

05:38 the estimate. Nobody has time to road

05:40 test a car for 20 minutes at high RPM.

05:43 Nobody gets paid for that. Nobody gets

05:46 paid for [music] that. Let that sentence

05:48 sit for a second.

05:50 What the Japanese discovered in 1984.

05:54 This is the part of the video where I

05:55 get a little nerdy. Fair [music]

05:57 warning. Stick with me because this is

05:59 the foundation of why the whole method

06:01 actually works. I have or

06:03 >> [music]

06:03 >> In 1984, Japanese automotive engineers

06:06 working with early catalytic converter

06:08 technology documented something that

06:10 would quietly influence factory

06:12 maintenance guidelines for decades.

06:14 During high load sustained highway

06:16 driving, catalytic converter bed

06:18 temperatures regularly exceeded 800°C.

06:21 At those temperatures, carbon deposits

06:23 don't just burn slowly. They combust

06:26 almost completely, leaving the precious

06:28 metal substrate surfaces clean and fully

06:30 reactive again. Toyota and Subaru

06:32 factory technical documents from the

06:34 late 1980s referenced this phenomenon in

06:37 the context of converter longevity.

06:39 Engineers noted that vehicles used

06:41 primarily for short urban trips showed

06:44 dramatically accelerated converter

06:46 degradation compared to vehicles that

06:48 regularly saw highway use.

06:50 The short trip vehicles were running

06:52 cold, never reaching the thermal

06:54 threshold needed to self-clean. [music]

06:56 The highway vehicles were accidentally

06:58 running a regenerational cycle every

07:00 time they merged onto a freeway. [music]

07:02 The chemistry behind this is

07:03 straightforward once you understand it.

07:05 Carbon deposits are essentially unburned

07:08 hydrocarbons that have polymerized onto

07:10 metal surfaces.

07:10 >> [music]

07:11 >> At low exhaust temperatures, typically

07:13 below 400°C,

07:15 those deposits are stable. They stick.

07:17 They accumulate. But above approximately

07:20 650°C,

07:22 those polymer chains break apart. The

07:24 carbon oxidizes.

07:26 >> [music]

07:26 >> The deposits convert to carbon dioxide

07:28 and water vapor and exit through the

07:30 tailpipe as harmless gas.

07:33 Your catalytic converter was literally

07:35 designed to reach these temperatures.

07:37 The precious metal substrate operates

07:39 most efficiently between 400 and 900

07:42 degrees Celsius.

07:43 The problem is that most American

07:45 drivers never give it the chance. Short

07:47 trips, low speeds, gentle acceleration,

07:50 city traffic. The converter warms up,

07:52 does partial work, cools down before it

07:55 ever reaches cleaning temperature,

07:56 [music]

07:57 and accumulates another thin layer of

07:59 deposits every single day.

08:02 40 years of Japanese engineering

08:04 documentation essentially confirms what

08:06 your catalytic converter has been trying

08:08 to tell you the entire time. It needs to

08:10 get hot. Really hot, consistently. And

08:13 most [music] of you have never let it.

08:16 The exact 20-minute protocol.

08:19 All right. This is the section you

08:21 actually came [music] for. I'm going to

08:23 walk you through this exactly the way I

08:25 did it. In exactly the way the

08:28 underlying engineering logic supports.

08:31 Before you do anything else, you need to

08:33 check one thing. Pull your oil dipstick

08:35 and look at what's on it. If you If your

08:37 oil is dark black and sitting below the

08:39 minimum line, stop reading [music] and

08:42 go do an oil change first.

08:44 Running this protocol with degraded oil

08:46 will push additional phosphorus and ash

08:48 compounds through your exhaust and

08:51 recoat the very surfaces you're trying

08:53 to clean.

08:54 Fresh oil matters. This entire method

08:57 assumes your engine is in reasonable

09:00 baseline health.

09:01 It is not a substitute for deferred

09:03 maintenance.

09:04 I cannot stress this enough. Also, check

09:07 your coolant temperature gauge works and

09:08 your car isn't running hot.

09:11 You're about to ask your engine to work

09:12 harder than it usually does.

09:14 >> [music]

09:15 >> Now is not the time to discover your

09:16 cooling system has a problem. Good. If

09:19 your maintenance is current, here's the

09:21 protocol. Step one, find a highway or a

09:24 long open road where you can legally and

09:26 safely sustain 60 to 70 mph. Not a

09:29 residential street, not a school zone. I

09:32 shouldn't have to say that, but here we

09:33 are.

09:34 Step two, let your engine [music] reach

09:36 full operating temperature before you

09:38 begin.

09:39 This means the temperature gauge is

09:41 sitting in its normal position

09:43 and has been there for at least 5 s 5

09:45 minutes.

09:46 >> [music]

09:46 >> Do not start this protocol from a cold

09:48 start. A cold catalytic converter hit

09:50 with sudden high heat can experience

09:52 thermal shock. You want a gradual

09:54 temperature ramp, not a shock. Drive

09:57 normally for 10 minutes first. [music]

09:58 Step three.

10:00 Once you're at highway speed and fully

10:01 warmed up, drop one gear manually if

10:04 you're driving an automatic.

10:05 Most modern automatics have a manual

10:07 mode or you can use the paddle shifters

10:09 if your car has them.

10:11 If you drive a manual, drop from fifth

10:13 to fourth or from sixth to fifth

10:15 depending on your gearing. The goal is

10:17 to raise your engine RPM to between

10:19 3,000 and 3,500 RPM while maintaining 60

10:24 to 65 mph. This is the sweet spot. High

10:27 enough RPM to generate serious exhaust

10:30 heat, not so high that you're screaming

10:33 the engine unnecessarily.

10:35 Step four. Hold that RPM range for a

10:37 sustained 20 minutes without stopping.

10:40 No traffic lights, no exit ramps, no

10:43 slowing for construction zones if you

10:44 can help it.

10:46 The sustained heat cycle is the entire

10:47 point. Every time you slow down and let

10:49 the exhaust cool, you interrupt the

10:51 process and the deposits restabilize.

10:54 You need 20 continuous minutes of

10:56 sustained high exhaust temperature to

10:58 trigger meaningful carbon combustion

11:00 inside the converter. Step five. [music]

11:03 Do not turn the car off immediately when

11:04 you finish. Drive normally for at least

11:07 five additional minutes at lower speeds

11:09 before parking. This allows the

11:11 converter to cool gradually rather than

11:13 trapping residual heat against the

11:15 substrate.

11:15 >> [music]

11:16 >> Rapid cool down after extreme heat can

11:18 cause micro cracking in the ceramic

11:20 honeycomb over time.

11:22 Let it breathe down slowly. That's the

11:24 complete protocol. [music]

11:26 20 minutes, no parts, no tools, no

11:29 appointment. The most common mistake

11:31 people make is doing this on city

11:33 streets by revving the engine at red

11:35 lights.

11:36 >> [music]

11:36 >> That is not the same thing and it

11:38 actually causes more harm than good.

11:40 Revving a stationary engine pushes

11:42 unburned fuel into the exhaust stream

11:45 without the high exhaust flow rate that

11:46 highway driving creates. You need both

11:48 the heat and the flow. Highway speed

11:51 >> [music]

11:52 >> generates both simultaneously. The

11:54 second most common mistake is doing this

11:56 once and expecting a miracle. If your

11:59 converter has been accumulating deposits

12:01 for 60,000 mi of city driving, 1

12:04 20-minute highway run will improve it.

12:06 It probably won't completely restore it.

12:09 Repeat this protocol three times over 2

12:11 weeks for a seriously clogged converter.

12:13 Each session burns away another layer.

12:16 The lacquer thinner amplifier method.

12:20 Now we're getting into the part of this

12:21 video that makes some people

12:22 uncomfortable. That's fine. [music]

12:24 Stay with me because the chemistry is

12:26 real and the results are documented.

12:28 There is a fuel additive method that,

12:31 when combined with the heat cycle

12:32 protocol, dramatically accelerates the

12:35 decarbonization process inside your

12:37 catalytic converter.

12:38 It doesn't come in a bottle with a race

12:40 car on the label. It doesn't cost $30 at

12:42 the parts counter. It's lacquer thinner.

12:43 [music]

12:44 Specifically, acetone-based lacquer

12:46 thinner. The kind you buy at a hardware

12:48 store for about $8 per quart.

12:50 >> [music]

12:51 >> Before anyone comments that this sounds

12:53 insane, let me walk through the

12:54 chemistry.

12:55 Lacquer thinner contains a blend of

12:57 solvents, primarily acetone, toluene,

13:00 and methyl ethyl ketone.

13:02 When added to gasoline in precise small

13:04 quantities, these solvents alter the

13:07 combustion characteristics of the fuel

13:08 mixture in two useful ways. First, they

13:11 raise the effective combustion

13:12 temperature slightly, which means

13:14 exhaust gases entering the catalytic

13:16 converter arrive hotter than normal.

13:18 >> [music]

13:18 >> Second, and more importantly, they act

13:21 as a solvent carrier inside the

13:23 combustion chamber itself, breaking down

13:25 carbon deposits before they even reach

13:27 the converter. The deposits that do

13:30 reach the converter arrive in smaller,

13:31 less adherent form and combust more

13:34 readily at the temperatures your heat

13:35 cycle protocol generates.

13:38 Here is the exact ratio. Add 2 oz of

13:40 acetone-based lacquer thinner

13:42 >> [music]

13:42 >> per 10 gallons of fuel, not more. The

13:45 goal is a slight solvent presence in the

13:47 combustion process, not a wholesale

13:49 change to your fuel chemistry. Too much

13:51 lacquer thinner can damage rubber fuel

13:53 system components and degrade injector

13:56 seals. 2 oz per 10 gallons sits well

13:59 below any threshold of concern,

14:01 according to fuel systems engineers

14:03 who've published on this topic in the

14:04 SAE technical database. Add the lacquer

14:07 thinner to your tank before you fill up

14:09 with fuel so it mixes thoroughly as the

14:12 gasoline goes in.

14:13 Then run your heat cycle protocol as

14:15 described. The combination of elevated

14:17 combustion temperature, solvent carrier

14:19 action, and sustained high exhaust flow

14:21 creates a cleaning environment [music]

14:22 inside your catalytic converter that

14:25 either method alone can't fully

14:27 replicate. [music]

14:28 What does this feel like from inside the

14:30 car?

14:31 Honestly, for the first few minutes,

14:32 nothing dramatic.

14:34 Around the 8 to 12-minute mark of the

14:36 heat cycle, if your converter was

14:37 significantly clogged, you may notice a

14:40 brief sulfur or burnt smell from the

14:42 exhaust.

14:43 That's the carbon deposits combusting.

14:45 It's temporary. It means it's working.

14:47 Some people describe it as a brief

14:49 rotten egg smell. Others say it smells

14:51 like a campfire for about 90 seconds.

14:54 Either way, it passes and what's

14:55 happening during those 90 seconds is

14:57 40,000 mi of accumulated deposits

15:01 burning off the precious metal substrate

15:03 surface. After the heat cycle, some

15:05 vehicles show visible wisps of white or

15:07 gray smoke from the exhaust for a minute

15:09 or two. Again, this is the combustion

15:11 byproducts clearing. Let the car idle

15:13 for a few minutes after parking and it

15:15 clears completely. One critical note, do

15:17 not use lacquer thinner in a vehicle

15:19 that uses a flex fuel system rated for

15:21 E85 ethanol blends.

15:24 The solvent chemistry interacts

15:25 differently with ethanol-heavy fuels.

15:27 Standard gasoline vehicles, including

15:29 those rated for E10, which is nearly

15:32 every car on the road in America, are

15:34 fine at the 2 oz per 10 gallon ratio.

15:37 How to know if it worked?

15:39 Here's the honest answer. You might not

15:41 know immediately. The check engine light

15:43 that brought you to this video was

15:45 [music] triggered by the downstream

15:46 oxygen sensor reporting inefficiency.

15:49 That sensor is comparing the oxygen

15:50 content of exhaust entering the

15:52 converter [music] to the oxygen content

15:54 exiting it. A clean, fully functional

15:57 converter consumes oxygen aggressively

15:59 during the conversion reactions. A dirty

16:01 [music] one lets more oxygen pass

16:03 through unreacted. The computer notices.

16:06 The light comes on. After your heat

16:08 cycle protocol, the converter needs time

16:10 to demonstrate its restored performance

16:12 to the computer. The computer doesn't

16:14 instantly recognize improvement. It runs

16:16 a series of readiness monitors over your

16:19 next several drive cycles before it

16:21 re-evaluates the catalyst efficiency and

16:24 either clears the code or keeps it

16:26 active. For most vehicles, if the method

16:28 worked, the check engine light

16:30 extinguishes on its own within two to

16:32 four days of normal driving following

16:34 the protocol. Not immediately. Two to

16:36 four days. Uh my light went off on the

16:38 second day. I've heard from people who

16:40 waited four days before they saw it go

16:42 dark. One guy emailed me to say his took

16:44 five days and then he panicked and then

16:46 it went off on day six.

16:48 Patience. The physical signs you can

16:50 check before the light clears.

16:53 Start the car cold and let it idle.

16:55 A partially unclogged converter often

16:57 produces a slightly rough idle due to

16:59 back pressure in the exhaust system.

17:01 After successful cleaning cycle, idle

17:03 typically smooths out noticeably. It's

17:05 uh subtle, but it's there. If you've

17:07 been living with a stumble at idle for

17:09 months, you'll notice the difference.

17:11 And the acceleration test. Get onto a

17:13 highway entrance ramp and accelerate

17:14 hard from 40 to 70 mph. A [music]

17:17 clogged converter creates back pressure

17:20 that restricts exhaust flow and kills

17:22 power delivery, especially in the mid

17:24 RPM range.

17:25 >> [music]

17:25 >> After cleaning, that restriction lifts.

17:27 The car pulls harder. Some people

17:29 describe it as feeling like they got a

17:30 new engine. I'd say it feels more like

17:32 someone finally opened a window that had

17:34 been stuck for 2 years. If you have

17:36 access to an OBD-II scanner, check the

17:39 live data on your downstream oxygen

17:41 sensor,

17:41 >> [music]

17:41 >> which is the sensor after the converter.

17:44 A healthy, clean converter produces a

17:46 downstream oxygen sensor reading that

17:48 stays relatively flat and stable

17:50 compared to the upstream sensor, which

17:52 oscillates rapidly. If your

17:54 post-cleaning downstream sensor reading

17:56 has shifted toward that stable pattern,

17:58 the converter is functioning properly

18:00 again.

18:01 That's the data confirmation.

18:03 Ah, when this won't work and what to do

18:06 instead.

18:08 I want to be straight with you here

18:10 because this channel doesn't hide the

18:11 limits of what it recommends. The heat

18:14 cycle and lacquer thinner protocol works

18:16 on clogged catalytic converters.

18:19 >> [music]

18:19 >> It does not work on physically destroyed

18:21 ones. There is a difference and you need

18:23 to know how to tell them apart before

18:25 you spend 3 weeks running highway

18:27 protocols on a converter that needs

18:29 replacement. Physical destruction

18:31 happens in specific identifiable

18:33 scenarios. The first is impact damage.

18:36 Your catalytic converter sits low on the

18:38 underside of the vehicle. In many cars,

18:40 it sits barely 4 in from the ground. A

18:43 serious impact with road debris, a curb

18:46 strike, or a hard bottom out can crack

18:48 or collapse the internal ceramic

18:50 honeycomb. When that happens, chunks of

18:52 substrate break loose and either lodge

18:54 inside the converter, restricting flow

18:56 catastrophically, or get pushed

18:58 downstream and damage your oxygen

19:00 sensors. If you hit something hard and

19:02 your check engine light came on within

19:04 24 hours of that impact, don't run the

19:06 protocol. Get underneath the car

19:08 >> [music]

19:08 >> and physically inspect the converter

19:10 shell for dents. The second is coolant

19:13 contamination.

19:14 >> [music]

19:14 >> If your head gasket has failed and

19:16 coolant has been entering your

19:17 combustion chambers, the resulting steam

19:19 and coolant compounds coat the catalytic

19:21 substrate with a silicate glaze that no

19:24 amount of heat will remove.

19:25 >> [music]

19:26 >> The glazing is chemically bonded to the

19:28 precious metals. It's permanent. The

19:30 symptoms of a coolant contaminated

19:31 converter include sweet-smelling white

19:34 exhaust smoke that doesn't clear after

19:35 warm-up and a check engine light

19:37 accompanied by coolant loss that you

19:39 can't trace to an external leak. Fix the

19:41 head gasket first, then deal with the

19:44 converter. The third is oil consumption

19:46 damage. Similar to coolant

19:48 contamination, but with phosphorus

19:50 compounds from engine oil. [music] If

19:52 your engine is consuming more than a

19:53 quart of oil per 1,000 mi, the

19:56 phosphorus additives in that oil are

19:58 steadily poisoning your catalytic

20:00 converter surfaces.

20:01 The heat cycle protocol can slow this

20:04 process and temporarily restore some

20:06 function, but it won't overcome active

20:08 ongoing contamination. If your engine

20:10 has a serious oil consumption problem,

20:12 the converter is a symptom, not the root

20:14 cause. Me, how do you tell a clogged

20:17 converter from a destroyed one without a

20:19 $1,000 diagnostic? The back pressure

20:21 test. Find the oxygen sensor port

20:24 upstream of your converter, which is the

20:25 first bung in the exhaust pipe before

20:27 the converter shell. Remove the sensor

20:29 temporarily and insert a vacuum gauge

20:31 hose adapter. At idle, exhaust back

20:34 pressure in a healthy system should be

20:36 under 1 PSI. On a seriously clogged

20:38 converter, you'll see 2 to 4 PSI or

20:41 higher. On a physically destroyed or

20:43 collapsed converter, you'll sometimes

20:45 see almost no back pressure at all

20:47 because the gases are bypassing the

20:49 substrate entirely through the collapsed

20:51 sections. Zero back pressure on that

20:54 test with a P0420

20:56 code is a strong indicator of physical

20:59 failure, not clogging. [music]

21:01 The maintenance habit that keeps your

21:03 cat clean forever.

21:06 Here's the part of the video that saves

21:08 you from having this conversation with

21:09 yourself again in 3 years.

21:12 The fundamental reason catalytic

21:13 converters clog is thermal deprivation.

21:17 Short trips, low speeds, gentle driving,

21:19 urban stop-and-go, the converter never

21:21 gets hot enough to self-clean. Deposits

21:23 accumulate because the operating

21:25 conditions never trigger combustion of

21:27 those deposits. You could have the

21:29 cleanest fuel, the freshest oil, and a

21:32 perfectly tuned engine, and a diet of

21:34 nothing but 8-mile round trips to the

21:37 grocery store will still slowly strangle

21:39 your converter. The prevention protocol

21:41 is almost insultingly simple. Once per

21:43 week, take your car on a 20-minute

21:45 highway drive. Not a highway cruise

21:47 where you're doing 55 in the slow lane

21:49 behind a delivery truck, a genuine

21:51 sustained 60 to 70 mph drive in a gear

21:54 that puts your RPM between 2,500

21:58 and 3,000. This doesn't need to be the

22:00 full heat cycle protocol with lacquer

22:02 thinner.

22:03 >> [music]

22:03 >> This is just normal highway driving done

22:05 with intention and consistency. You're

22:07 allowing your converter to reach and

22:08 sustain its operating [music]

22:09 temperature range. You're triggering

22:12 natural self-cleaning. You're doing

22:14 exactly what the Japanese engineers

22:15 documented in 1984. If your life

22:18 genuinely doesn't allow for a weekly

22:20 highway drive because you live in a city

22:22 and never need to leave it, the lacquer

22:24 thinner treatment at the 2 oz per 10

22:26 gallon ratio run every 6 months

22:29 accomplishes much of the same protective

22:31 function. It's maintenance, [music]

22:33 not repair.

22:34 The difference between those two

22:35 categories is usually about $900. Fuel

22:39 quality matters more than most drivers

22:41 realize.

22:41 >> [music]

22:41 >> Top Tier gasoline, which is a

22:44 certification you can look up by brand

22:45 at the Top Tier website, contains

22:47 detergent additive packages at

22:49 concentrations that exceed federal

22:51 minimums. Those detergents reduce

22:53 combustion chamber deposits, which

22:55 reduces the volume of contaminated

22:57 exhaust gases that your converter has to

22:59 process. The difference between Top Tier

23:01 and a non-top-tier fuel is not dramatic

23:04 on a per [music] tank basis. Over 50,000

23:07 mi, it's the difference between a

23:09 converter that's functioning at 90% and

23:11 one that's functioning at 60%. Check

23:14 your air filter every 15,000 mi. A

23:17 clogged air filter richens the fuel

23:19 mixture, pushing unburned hydrocarbons

23:21 into the exhaust stream in higher

23:23 concentrations. Your converter handles a

23:25 certain load of unburned hydrocarbons as

23:27 part of normal operation. Push that load

23:30 above its capacity, and the excess

23:32 deposits on the substrate. An $8 air

23:34 filter is converter maintenance. Most

23:36 people don't think of it that way.

23:38 Finally, address oil consumption early.

23:40 If you're adding oil between changes,

23:42 find [music] out why. Worn valve seals,

23:44 worn piston rings, a leaking turbo seal

23:47 on turbocharged engines.

23:49 >> [music]

23:49 >> Any of these conditions are slowly

23:50 poisoning your converter with every mile

23:53 you drive. The repair you're avoiding to

23:55 save money today is building toward the

23:57 repair you'll be forced to make tomorrow

23:59 at 10 times the cost. I know that's not

24:01 a fun thing to hear. It is true. 3

24:03 months ago, a dealership told me my

24:05 catalytic converter was dead and handed

24:07 me a quote for $1,200.

24:10 I drove home. I checked my oil. I found

24:12 a long empty stretch of highway.

24:14 >> [music]

24:14 >> I drove for 20 minutes at 3,000 RPM. I

24:17 repeated that twice over the following 2

24:19 weeks. On the second day after the third

24:21 run, the check engine light went off on

24:23 its own while I was sitting at a red

24:25 light. I actually laughed out loud in

24:26 the car. The guy in the lane next to me

24:28 probably thought I was having some kind

24:29 of episode. Honestly, [music] fair. That

24:32 converter is still working today.

24:35 I have driven over 9,000 mi since that

24:37 dealership visit. The light has not

24:39 returned.

24:41 Total cost of the repair?

24:42 $0 and approximately 60 minutes of

24:45 highway driving spread over 2 weeks.

24:47 That is what Car Care Garage is here

24:49 for. Not to sell you products, not to

24:51 tell you everything is fine when it

24:53 [music] isn't, not to pretend that every

24:55 repair requires a shop visit and a

24:57 credit card. This channel exists because

24:59 the information gap between what

25:01 mechanics know and what drivers know is

25:04 costing American car owners billions of

25:07 dollars every single year. And most of

25:09 the time bridging that gap costs nothing

25:12 but the willingness to understand what

25:14 your car is actually telling you.

25:16 If this video has just saved you from

25:18 writing a four-figure check for a

25:19 converter that only [music] needed a

25:21 proper cleaning, hit that like button,

25:23 subscribe to Car Care Garage, and share

25:26 this with someone you know who's been

25:27 quoted a crazy number for a repair that

25:30 might not need to happen. And before you

25:32 go,

25:33 our next video exposes the engine oil

25:35 interval myth that's quietly destroying

25:37 engines that should last [music] 300,000

25:39 mi. Watch it before your next oil

25:41 change. You need to hear this.