DIY fuel additive to help clean catalytic converter

[FDMaguire]

I read this thread here:
https://bobistheoilguy.com/forums/threads/chemistry-of-catalytic-converter-cleaning.354488

I was tempted to post my question on this thread. But, it was not a perfect fit to the original purpose of that forum thread. I was also a bit cautious to add to a thread that had been quiet for a while.

I am dealing with the classic P0240 code. I am going to add a mixture to my gas tank to see if this can help clean the catalytic converters. This builds on watching and reading about the whole area of adding lacquer thinner to your gas that Scotty Kilmer's video got the most attention on this issue with millions of view that he first posted something like 12 years ago.

I believe uing the "lacquer thinner" term here creates confusion because what makes up lacquer thinner has changed for many locations where you buy it today. And, it can even be different depending on where you are purchasing today. Learning what was the make up of the original form of lacquer thinner that Scotty Kilmer was using combined with other research I did, I have decided to go with a 50/50 mix of toluene and naphtha.

But, I had also considered Xylene as either part of this mix or to replace the naphtha. I am curious to hear the thoughts of anyone here that might be smarter than me about Xylene on this thought. Certainly wish I had far more chemistry background than I do.


Also, to run some comments off at the pass, let me add the following:
1. Yes, I have read plenty about the concern that this might damage other parts on the car. I gravitate toward two general trains of thoughts here. First, I am going to add this mixture to the car and do straight run out of using the entire gas in a single shot on the freeway so it will not be sitting in the car/systems for a long time. Second, if it does take out something like a fuel pump, etc. for being in that short of a period of time, it was probably a system already nearing the end of the road nad I am fine replacing such given we intend to keep this car in the family for a long time.

2. The mix I am using is a 1 to 10 ratio of this DIY mix with regular gasoline.

3. No expectation of a guaranteed result here. It is simply one step. If this is not the solve, I have an incremental additional series of steps I will be doing. This also follows on some diagnostics already done.

 

[SubieRubyRoo]

Why not use CataClean that’s formulated for that and is safe?

 

[slacktide_bitog]

Why not use CataClean that’s formulated for that and is safe?

This.

Cataclean or CRC Guaranteed to Pass

 

[Mewbs]

I'd get a 3 pack of BG 44K and run on can per tank fill. You can get them at Amazon or Ebay from legit online dealership sellers, which is where I stock up from.

 

[joegreen]

I know adding to the tank is easy. But do you have access to clean out the cat manually. Maybe even through an o2 bung?

 

[Jetronic]

What are we cleaning out of the cat anyway? Soot can be done easily, but ash is a lot harder and I don't know if phosphor poisoning can be reversed

 

[SHOZ]

Good luck getting any cleaner though the combustion process. I poured a gallon of 50/50 toluene/xylene slowly though my Accent's cat directly into it through the pre cat O2 sensor bung. It's mounted vertically in front. Did no good. A $125 new AfterMarket cat did from eBay. 4 years running now.

 

[chemman]

Of all the chemicals you mentioned, toluene, naptha, and xylene, xylene would be the best for cleaning.

However, as @SHOZ mentioned, little if any xylene will survive the combustion process and get to the catalytic converter to perform any actual cleaning. Additionally, any xylene that does make it to the catalytic converter would suffer the same fate that unburned gasoline does - it will be oxidized and decomposed by the catalyst.

My best "recommendation" would be to fill up your gas tank with a Top Tier brand of the manufacturer's recommended octane for your vehicle and then go for a couple hundred mile trip on the interstate in order to get the catalytic converter good and hot enough to allow it to burn off any soot residues that are present on the surface of the catalyst.

 

[FDMaguire]

Let me first answer some of these postings to just point out that a ton of people have had success with putting different types of additives into the fuel tank of their vehicle to impact passing inspection. No one is saying it is a 100% guaranteed in the least but a ton of people have had success with this.

When it comes to Cataclean or CRC Guaranteed to Pass, this still remain some composition of liquids where you are paying a premium to get very little actual content. This DIY approach allows for far greater amount of liquid at much less cost. I am not hard opposed of these specific products and know of both well. But, as referenced, tons of people have had success with other routes with things off the shelf not designated specifically for cleaning a catalytic converter and far cheaper. What we are really talking about here is kind of doing an 'open recipe' of what is likely the really meaningful components making an impact that are in the Cataclean or the CRC Guaranteed to Pass type of products.

I realize that there could be a whole debate here on whether the whole "lacquer thinner" into your tank is a good idea or can work at all. That has been discussed extensively in some different places online. I am not really trying to get into that debate here. I am was just looking into more insight of Xylene versus toluene and naphtha. Text is terrible for tone so please only read that in the positive.

And, that as a debate topic on whether additive to your fuel tank to help pass inspecition actually works might make a great forum topic thread all to itself for those interested. Another potential interesting topic thread is the different positions pro and con on cleaning out a catalytic converter by removing from the vehicle and dunking in different kind of solutions with different kinds of steps. For this later topic, there has even been some formal research paper work done on a DIY approach. Both of those topic areas have been well discussed in other corners of the internet. I have essentially reached my own conclusion on both of these areas after a ton of research.

What I am really interested in is this area of what you might ask what could be the best mixture if we were creating the "open recipe" of some of these commercial products and where 'good enough' was really plenty fine.

 

[FDMaguire]

Of all the chemicals you mentioned, toluene, naptha, and xylene, xylene would be the best for cleaning.

However, as @SHOZ mentioned, little if any xylene will survive the combustion process and get to the catalytic converter to perform any actual cleaning. Additionally, any xylene that does make it to the catalytic converter would suffer the same fate that unburned gasoline does - it will be oxidized and decomposed by the catalyst.

My best "recommendation" would be to fill up your gas tank with a Top Tier brand of the manufacturer's recommended octane for your vehicle and then go for a couple hundred mile trip on the interstate in order to get the catalytic converter good and hot enough to allow it to burn off any soot residues that are present on the surface of the catalyst.

@chemman. Not at all challenging your statement of "xylene would be best for cleaning". Just asking your 'why' here that you say it would be best for cleaning. Trying to understand this from a chemistry perspective.

 

[FDMaguire]

I know adding to the tank is easy. But do you have access to clean out the cat manually. Maybe even through an o2 bung?

@joegreen In researching a bunch, what you would put in the fuel tank as an additive to potentially impact the catalytic converters for passing inspecition is seen by many as very different of what you would put as a mixture formulation to directly feed into the catalytic converter.

Directly seeking to clean the catalytic converters is really an interesting topic all to itself that even includes a research paper dedicated on that specific topic area with a DIY formulation. If I would go to this step, I would only do it by fully removing the catalytic converter where I could fully submerge the catalytic converter, do so with a heated fluid medium, and have some process steps over a period of time.

Happy to add more on what I found on my research for this but would prefer that be on a different topic forum. Glad to add to such if you want to start that as a new forum topic.

 

[FDMaguire]

Good luck getting any cleaner though the combustion process. I poured a gallon of 50/50 toluene/xylene slowly though my Accent's cat directly into it through the pre cat O2 sensor bung. It's mounted vertically in front. Did no good. A $125 new AfterMarket cat did from eBay. 4 years running now.

@SHOZ If I was going for direct cleaning of the catalytic converter, I would not go the toluene/naphtha route or consider the toluene/xylene route either. I am only looking at this for a formulation to go into the gas tank itself and then through the combustion process.

 

[chemman]

@chemman. Not at all challenging your statement of "xylene would be best for cleaning". Just asking your 'why' here that you say it would be best for cleaning. Trying to understand this from a chemistry perspective.

Toluene has one methyl group attached to the base molecule whereas xylene has two methyl groups. The addition of the second methyl group makes it a more powerful solvent for cleaning carbon based deposits relative to toluene.

It used to be (and may still be) that the most potent carburetor cleaners for soaking carburetors in before rebuilding them contained lots of xylene compounds. (Xylene is a mixture of positional isomers where the second methyl group is attached to a different position relative to the methyl group in toluene.)

Don't get me wrong - toluene is a strong solvent (I've used a lot of it in the lab), but xylene is stronger.

Hope this helps.

 

[FDMaguire]

Toluene has one methyl group attached to the base molecule whereas xylene has two methyl groups. The addition of the second methyl group makes it a more powerful solvent for cleaning carbon based deposits relative to toluene.

It used to be (and may still be) that the most potent carburetor cleaners for soaking carburetors in before rebuilding them contained lots of xylene compounds. (Xylene is a mixture of positional isomers where the second methyl group is attached to a different position relative to the methyl group in toluene.)

Don't get me wrong - toluene is a strong solvent (I've used a lot of it in the lab), but xylene is stronger.

Hope this helps.

@chemman Thank you so much!!!

So, if you will allow me, where would naphtha fit into this mix?

I arrived at the toluene and naphtha combination by going on what others posted was the original product used by Scotty Kilmer in terms of what he was putting into the gas tank as 'lacquer thinner' years ago when he posted that video.

I am well outside my area of strength here with so little chemistry background. Not that I have zero with some classes in college and growing up in my parent's machine shop with all sorts of stuff around us. But, that still is pretty limited.

I am also left to wonder then why not just go 100% Xylene.

I realize that I am asking that of you while your previous comments seems to point toward you believing that this approach of a fuel additive to improve catalytic performance is something you do not put much weight in making an impact. I am certainly not trying to hard challenge you on this and appreciate there are many people online that feel that approach can make almost no impact and another cluster that feels like their experiences says it can at times.

So, maybe what I am asking is for you to live in a theoritical world for a moment where you thought it might make an impact, what would be your thoughts on the best DIY mix of what you can buy off the shelf? Having said this, toluene itself is not even something readily available to everyone depending on where they live. Although it can be obtained with some extra steps even for those of us in states that are making toluene availablity to the general public more difficult.

 

[chemman]

@FDMaguire - man you are really making me put my thinking cap on today!

Well naptha is not a single compound. Naptha is a mixture of various liquid hydrocarbons primarily composed of compounds containing between 5 and 9 carbon atoms per compound. It has also been described as a middle distillate cut from the distillation of crude oil, and makes up between 15 - 30% of crude oil by weight. It is a major combustible part of both gasoline and kerosene.

That being said, since gasoline can be used as a solvent, it will do some cleaning of dirt and residues left behind by the combustion process. However, as has been discovered, it is not a very strong solvent for things like varnishes and gums that can foul various components of fuel systems (e.g. carburetor jets, carburetor passages, fuel injectors, etc.).

So, based on what I remember from being educated in the classroom, and my work with the leftovers (some really nasty stuff) from the conversion of coal to liquid fuels in the laboratory, I would rank the 3 compounds of interest, weakest to strongest as naptha, toluene, and xylenes.

Remember, xylene, or more properly xylenes, in order to be "an affordable solvent" is a mixture of 3 different xylene isomers (separating each isomer from the other 2 isomers is likely a challenging endeavor, and making a single isomer requires extra synthesis steps in a patented process. So, when you purchase a product containing xylene, you will likely be purchasing a product containing a mixture of the three xylene isomers.

Just remember all of the solvents mentioned are extremely flammable and toxic!!!! So please be very careful when using them and minimize skin exposure by using proper protective equipment like nitrile glove, work in a well ventilated environment, be sure to wear eye protection, and an appropriate respirator if in a confined space.

 

[FDMaguire]

@chemman This is exactly what I was hoping to learn by posting over here. Again, thank you so much. Also appreciate learning a more specific understanding of the three different xylene isomers.

From what you have shared with me, I think I would go with Toluene and Xylene in a 50/50 mix next time if I was doing this again. For this time (fair chance my last time), I have already ordered the Toluene and the Naphtha for this round. I still wonder if going just straight Xylene might even be the answer.

I do not think it is a do or die in terms of what I am picking as a mix here between these three options. My suspicion is that most of this result people are getting is simply by getting higher octane and larger raised temperatures hitting the catalytic converters by doing a straight aggressive run on the freeway for 150 plus miles after putting in the fuel additive. Not a super expert so not making some hard declaration but just what I suspect.

I will say that I do not think people should be going with what is often today's lacquer thinner after watching things online (that were put up many, many years ago) where it is often that the majority is acetone in the lacquer thinner they are purchasing in these current days versus what often made up lacquer thinner in the past. That is a direciton I would not go at all. Having said that, all sorts of postings of people using lacquer thinner more recently that did get the result they wanted. So, maybe I just got all that wrong in terms of my thinking there.

And, yes, big thanks for all the warnings on interacting with these fluids. I had already planned for everything you are saying given other things I have read. But, still very smart for you to point out these cautionary notes and I should have done so already for those that might read this forum thread in the future.

 

[chemman]

Good Luck and please let us know how it works out for you!

 

[FDMaguire]

Good Luck and please let us know how it works out for you!

You bet. Will do.

 

[FDMaguire]

In terms of an update of how this worked out for me, the top line is that I got all the emission code engine light issues to go away long enough that I was able to get through inspection on a car that was well past due which was making it where we were not driving the car.

But, there are a lot of facts here that cannot imply a direct confirmation that this DIY fuel additive made the difference for our particular car and its performance issues.

My first step was clearing the codes on the car at the house and then starting my drive which including going to a store a bit of distance away to pickup the two fuel additive items. In this clearing of the codes, it was just done via my Torque app on my phone via the OBD2 bluetooth adapter.

On the first part of this drive, I gave the car what some refer to as the "Ferrari treatment" meaning I purposefully kept it at higher RPMs. That was mainly done by selecting "3" versus the normal drive setting that kept my RPM often in the 3K to 3.5K range for times I was not on the freeway. Well, after just 23 miles, all my emission code items showed ready. Frankly, I was surprised that it get all the triggers it needed during that time to go from "Incomplete" to "Complete" status.

I drove a little over another 100 miles. I was often driving in the 75 to 80mph range on the freeway for that part of the drive but obviously in the normal drive selection. Again, this is the whole discussion in the corners of some of the internet forums about giving the vehicle the "Ferrari" treatment. The emission codes stayed all positive during this.

At the end of that drive, I added the 50/50 fuel additive at a roughly 10 to 1 ratio and disconnected the battery for 20 minutes. I am frankly not sure if that 20 minutes is even needed or not to fully clear the ECU versus just a few seconds. But, some people specifically referenced having the battery disconnected for a longer time so I followed such.

I then drove on that half full tank with the fuel additive for roughly another 120 miles with the emission codes all staying great and no check engine light. I was either on the freeway driving the speeds referenced. Or, when on side roads, I would often drop it into 3 versus traditional drive setting to keep the RPM's higher on the engine.

The car passed annual inspection without a problem.

But, now the however, I drove just another approx. 5 miles after the car inspection to a place to fill up the tank. I had driven only a few more miles after getting this fuel and the light came back on.

I then cleared the codes again with the Torque app and gave it some more of the "Ferrari treatment". And, around 25 miles later, all the emission code checks showed in a ready status and it would be good to pass inspection again.

So, I am not sure anything can be said for sure about the DIY fuel additive making a difference in our situation. For my particular car in his current performance status, it could have been as easy as just clearing the codes with the Torque app, giving it the Ferrari treatment for 30 miles or so where all the emission checks cleared as "Ready", and then pass inspection. So badly which I had known that around 2 months ago so it would not have sat with the mechanic as long as it did.

Of course, I do not think the problem is gone. If I had a suspicion, it is that the system is sitting on the edge in terms of emissions performance and the Ferrari treatment means it can be put in a fine state to pass inspection. And, maybe the DIY fuel additive is helping some here and maybe not. But, once back to the frequent slower driving miles on country roads this car sees a great deal in normal use, the check engine light will likely keep coming back on.

And, could I do this Ferrari treatment next year for inspection and the year after that and after that and the car show all "Complete" status on the emission checks? Maybe. Maybe not. No doubt others would have opinions on this but I not think anyone could know for sure at this point.

 

[FDMaguire]

Having done a bit of a deep dive here on emission codes in working my own problem, I see a subset of people online making all these declarative comments about what does and does not work which I think is a bit foolish.

The fact is there are a lot of variables at play and I think the proverbial wisdom of "it depends" is really the biggest thing to know.

From there, it is what is the branching possibilities of options to explore to fix the problem. And, those decisions are also impacted in terms of how important is to keep total cost the lowest, value of time as part of this (both ones own time and the value of total time to get the car inspecition ready), and ones own ability and/or enjoyment of working on mechanic issues.

A good discussion about this with a highly seasoned mechanic brought the fair insight that few mechanics are going to mention these other possibilities in terms of helping get past an inspection because they are not guaranteed to work and could make liability for them. And, one can easily see how a less informed customer could blame them for things that are not really the mechanics fault or expect absolutes in fixes with some of these strategies that no one can provide.