Fuel injector cleaners tests

[sciguyjim]

These tests were done by me to help determine the best products:

Background about tests:

As a worst case sample of material which might be found in gasoline I used ordinary tar. The brown deposits we find coating carburators, and which collects in fuel injectors and on intake valves, are the highest boiling components in gasoline. They are tar-like materials which distilled along with the lighter gasoline. The best solvent I've ever seen for these was methylene chloride, but it's expensive and I'm sure it's being phased out to protect our ozone layer. In any case, if you used it on a modern car the chlorine freed during combustion would corrode the oxygen sensor. Amoco advertises a cleaner gasoline and I'm sure it's because they've reduced these tar-like compounds. All gas these days contains at least a little detergent of some sort to help keep these deposits from building up too much.

Dimethylformamide is listed in the literature as being a good engine cleaner and is "especially good at dissolving carbonaceous deposits". I haven't used this myself because it is a bit too toxic. Instead I used N-methyl pyrrolidone, which is also good.

For my tests, I tried to use a wide variety of products, well known and unknown, expensive and cheap, and also some pure solvents in order to represent a good cross section of products on the market. Note, carbon itself (such as soot and other thermally decomposed material) is not soluble in ANY solvent but solvents like dimethylformamide and N-methyl pyrrolidone do a good job of breaking up clumps and dispersing the fine particles to release the heavy tarry materials trapped within them. However, some of these solvents are too harsh to use freely in the fuel system. (Someone in one of these forums told me that when the auto industry looks for good cleaners, they mostly look for solvents that will not attack the plastic and rubber parts in the system.)

Most cleaners (the safer & slightly less effective ones) usually have common solvents in them like toluene, alcohol, acetone or methyl ethyl ketone, and naphtha. If you want to use these to clean your system, you can get more for your money by buying the pure solvents at a hardware store and mixing them yourself. I have never had a problem adding toluene, acetone, alcohol, or naphtha to my gas tank in quantities up to one quart per 16 gallons.

Most of the straight solvents I used are at least as flammable as gasoline so be careful if you use them. The alcohol used was pure, 100% isopropyl alcohol. This has no water in it, it is not the same as "rubbing alcohol".

These test results are as fairly and accurately done as I could manage with the equipment I had available, and the other data presented is also accurate to my knowledge. Your car may have different plastics in it than mine does so if you choose to make your own cleaner, do it at your own risk.

TEST RESULTS

RELATIVE EFFICIENCIES AT WHICH VARIOUS CLEANERS WILL DISSOLVE HIGH BOILING RESIDUES FROM GASOLINE AND CARBONACEOUS DEPOSITS FOUND IN USED MOTOR OIL, (10=BEST):

· 10 Gunk Gas Treatment
· 10 Toluene (a common ingredient)
· 9 Castrol Syntec Power System
· 8 Duralube Fuel System Cleaner
· 7 Gunk Fuel Injector Cleaner
· 6 Redline SI-1
· 5 Gunk Air Intake Cleaner
· 4 Naphtha (a common ingredient)
· 4 STP Fuel System Cleaner
· 4 Seafoam Motor Tuneup
· 4 Trak Fuel Injector Cleaner
· 4 STP Intake Valve Cleaner
· 4 CD-2 Emission Cure
· 4 Prolong Fuel System Treatment
· 3 CD-2 Fuel Injector Cleaner
· 3 Techron Concentrate
· 0.5 Butyl Cellosolve (a COMMONLY used "AUTO INDUSTRY DETERGENT" for oil and grease)

THE FOLLOWING CLEANERS DO NOT HURT NYLON (LISTED RANDOMLY).
(The letters in parentheses indicate how well they dissolved the material from used oil, A=best.):

· Toluene (A)
· 2-Phenoxyethanol (A)
· Duralube Fuel System Treatment (B)
· B-12 Chemtool (B)
· Trak Fuel Injector Cleaner (C)
· Techron Concentrate (D)
· STP Intake Valve Cleaner (E)
· Seafoam Motor Tuneup
· CD-2 Emission Cure
· Prolong Fuel System Treatment
· Aromatic distillates
· Naphtha
· Butyl cellosolve
· Acetone

THE FOLLOWING CLEANERS WILL DECOMPOSE THE NYLON SOCK IN THE FUEL TANK. Listed in order of increasing severity:

· STP Fuel System Treatment
· CD-2 Fuel Injector Cleaner
· Gunk Fuel Injector Cleaner
· Castrol Syntec Power System
· Redline SI-1
· Gunk Gas Treatment
· Monoethanolamine
(The monoethanolamine is the worst here. It turns nylon black on contact. It is significant to note here that the "best" "detergents" in use today are similar, strongly alkaline organic solvents). Another use for the current bunch of organic amine "detergents" is cleaning deposits out of cylinders, so I hear.

I hope this takes the guesswork out of choosing good products.

[higgimonster]

Thats awesome. I have been wondering about these fuel additives and whether they actually worked or not. this should make choosing one a bit easier. Thanks a lot for the info.

[JUNKPILOT]

Originally posted by sciguyjim
These tests were done by me to help determine the best products

According to this test, it looks like Duralube is the best cleaner that won't harm nylon fuel system components. I do not know if my car uses nylon components in the fuel system.

Can you provide more detail on how you conducted the tests? I appreciate your scientific approach to this matter... I use the Chevron Techron fuel cleaners, but have to rely solely on their data.

[TerminalVelocity]

defentally usefull to know :bandit:

[sciguyjim]

Originally posted by JUNKPILOT


According to this test, it looks like Duralube is the best cleaner that won't harm nylon fuel system components. I do not know if my car uses nylon components in the fuel system.

Can you provide more detail on how you conducted the tests? I appreciate your scientific approach to this matter... I use the Chevron Techron fuel cleaners, but have to rely solely on their data.

To find out what's in your car's fuel system, call the mfgr's customer service dept & tell them what you want, maybe they can route you to a person who knows. That's what I did. They told me almost every kind of rubber o-ring in the system, including some kinds I'd never heard of.

The tests compared how well each product dissolved soluble gunk and how well they broke up lumps of insoluble carbonaceous material. The appropriate gunk was applied to an absorbent paper then the product was applied and allowed to soak past the spot of gunk. After a specific amount of product was applied, the distance it carried the gunk was measured.

[Polygon]

Shit! I have been using STP for a long time now, damn, time to change!

[bluetwo]

that certainly made for some interesting reading... i've been using techron fuel system cleaner concentrate for years. one contributing factor is that a family friend of ours has worked in their marketing dept for over 20 years...

my personal observations: i always add a bottle of techron before every oil change, run the tank dry, refill, and then change the oil. i'm always amazed at how black the oil gets when i compare the oil color on my dipstick before and after techron treatments. whether or not it is the best, i do not know. it does appear, however, that it is doing something!

[ivymike1031]

I keep forgetting to ask - did you test regular pump gasoline to see how effectively it dissolves your tar? If the tar is readily soluable in gasoline, this would bode poorly for using tar as the test material.

[sciguyjim]

Originally posted by ivymike1031
I keep forgetting to ask - did you test regular pump gasoline to see how effectively it dissolves your tar? If the tar is readily soluable in gasoline, this would bode poorly for using tar as the test material.

No, I didn't test gasoline, but I know for a fact that tar is soluble in it, certainly at the small quantities normally present in the gasoline. Gasoline, and other products manufactured from crude oil, are a complex mixture of many thousands of individual chemicals. Because of this complexity, it is difficult to easily refine the oil to get individual pure chemicals. The complexity also makes the gasoline a good solvent for other petroleum products. Any tarlike material which is found to be insoluble in gasoline or other common petroleum solvents would have to be changed considerably form its original chemical structure and so would not be a suitable candidate for the tests.

One of the reasons gasoline has its yellow-brown color is from traces of high boiling, high molecular weight compounds containing atoms of oxygen, nitrogen and sulfur. These "heteroaromatics" are the same compounds of which tar is composed.

When gasoline sprays out of the fuel injector tip, or when the car is shut off and the injector tips get a "hot soak", most of the gasoline vaporizes as it should. However, some of the traces of tar-like materials present do not vaporize because they naturally have very high boiling points. They remain on the tip and can build up over time. They can also be polymerized by the heat to form compounds more like "coke", soot and graphite. This is the same material which can build up on the backside of intake valves. The detergents added to gasoline and changes in fuel injector design have helped reduce the chance of having problems from this buildup.

The purpose of my tests was to identify products, and some individual solvents, which can be used to clean injector and cylinder deposits. The deposits cannot be changed too much from their original structure because as they polymerize they become insoluble in any solvent.

The trick is to find solvents which are cost effective, have compositions similar to the tarlike material (in a number of features), and which will not harm the various gaskets and seals used in the car. As with most things, there isn't one best answer. Compromises have to be made with the chemical properties of the solvents and the blends of solvents used.

So, you could say the gasoline is the source of both the problem and the solution.

[ivymike1031]

or "gasoline is the solution in which we find the problem?"

If none of the solvents dissolve tar better than gasoline does, why use any of them?

[sciguyjim]

Originally posted by ivymike1031
If none of the solvents dissolve tar better than gasoline does, why use any of them?

Because these tar-like compounds, while having some properties similar to gasoline, also have quite distinctive properties of their own. Certain solvents with these properties may work better than the hodge-podge mixture of stuff in gasoline.

[ivymike1031]

May work better... may not work better... who knows? I thought the point of the testing was to find that out? If all we know is that some of the solvents work better than others, but we don't know whether any of them works better than gasoline, then the most fundamental question ("should I ever even bother using this stuff") hasn't been answered.

[sciguyjim]

For one thing, I don't have access to all the chemicals used in the store bought products (except in the products themselves), and I don't have the facilities to do testing on a larger scale. Personally, I think most of the products do help clean like they're supposed to, though a lot of people don't believe these products are necessary at all. They feel if the car is tuned properly you should do fine with just basic maintenance and good quality gas with the proper octane rating. I did accomplish my goal of rating the store bought products, at least in lab tests if not in an actual engine. Part of the reason I chose some of the pure solvents was for my own curiosity and to see if I could choose acceptable solvents by the chemical properties I thought were important. Some of the solvents were similar to the product ingredients, which, as I said, I couldn't obtain easily.

[ivymike1031]

I still don't understand why you didn't test a sample of gasoline as a baseline...

[sciguyjim]

I guess I should have, I just didn't think of it at the time. How would I explain cleaning injectors by doing nothing but running more gas through them?