PTFE in lubricants - pro? con?

[CluelessFrank]

Hello, long time reader on these superb forums with a first post.

I still have some questions after using the search function, regarding the use of PTFE in liquid and semi-solid lubricants. I?m not interested in dry lubricants or PTFE "enhanced" engine oils, only multi-purpose oils, greases and gear oils.

I wasn?t too impressed in the past by the performance of PTFE containing multi-purpose oils and rather tend to doubt the claims regarding the effects of the PTFE made by the manufacturers, something I found partially confirmed reading through some posts here. I once used a PTFE fortified light grease -marketed as a gun specific product- of a well known brand for a while with very good results but stopped using it after I got some serious issues with corrosion. After some research I came to suspect that this product, at least at the time, contained a chlorinated compound -i.e. chlorinated paraffin- which might have been responsible for the good lubricating qualities rather than the PTFE; however, this was never confirmed nor denied by the manufacturer although they were very vocal before, praising the superiority of their product.

If I got the information right, PTFE suspended in an oil will be rather useless? ? No EP properties and no ability to cling to- and or coat the surfaces?

What about semi-solid lubricants like grease? I read that PTFE makes a good thickener. What about the asperities-filling claims ?in a paste formulation, not liquid-, creating a smoother surface to help a more stable film protecting the sliding parts? Does this hold any water? Is the smooth feeling a freshly greased mechanism may show rather due a temporary cushioning effect of the solid PTFE particles with no effective long term protection?

Some manufacturers use fumed silica in oils as well as in greases to form a matrix to keep the PTFE particles in suspension. Are there any known shortcomings using fumed silica in lubricants, like increased water absorbency for example or something? ? Any benefits of using fumed silica, on the other hand?

What about the claims of specially treated or shaped[I/] PTFE particles filling- or adhering to metal surfaces?

What is the verdict on PTFE containing lubricants?

Any input will be appreciated!
Thanks, Frank

 

[CluelessFrank]

Hello, long time reader on these superb forums with a first post.

I still have some questions after using the search function, regarding the use of PTFE in liquid and semi-solid lubricants. I'm not interested in dry lubricants or PTFE "enhanced" engine oils, only multi-purpose oils, greases and gear oils.

I wasn't too impressed in the past by the performance of PTFE containing multi-purpose oils and rather tend to doubt the claims regarding the effects of the PTFE made by the manufacturers, something I found partially confirmed reading through some posts here. I once used a PTFE fortified light grease -marketed as a gun specific product- of a well known brand for a while with very good results but stopped using it after I got some serious issues with corrosion. After some research I came to suspect that this product, at least at the time, contained a chlorinated compound -i.e. chlorinated paraffin- which might have been responsible for the good lubricating qualities rather than the PTFE; however, this was never confirmed nor denied by the manufacturer although they were very vocal before, praising the superiority of their product.

If I got the information right, PTFE suspended in an oil will be rather useless? - No EP properties and no ability to cling to- and or coat the surfaces?

What about semi-solid lubricants like grease? I read that PTFE makes a good thickener. What about the asperities-filling claims -in a paste formulation, not liquid-, creating a smoother surface to help a more stable film protecting the sliding parts? Does this hold any water? Is the smooth feeling a freshly greased mechanism may show rather due to a temporary cushioning effect of the solid PTFE particles with no effective long term protection?

Some manufacturers use fumed silica in oils as well as in greases to form a matrix to keep the PTFE particles in suspension. Are there any known shortcomings using fumed silica in lubricants, like increased water absorbency for example or something? - Any benefits of using fumed silica, on the other hand?

What about the claims of specially treated or shaped PTFE particles filling- or adhering to metal surfaces?

What is the verdict on PTFE containing lubricants?

Any input will be appreciated!
Thanks, Frank

 

[psudaytona]

To bond to metal you need very high temps and pressure I believe, something you can't get in an engine. Teflon containing adds/filter are useless. If you want to add something to your oil try

Lubecontrol 20
VSOT
or SLOB.
All will make your engine MUCH happier(esp LC20)

 

[CluelessFrank]

Thanks for your reply, psudaytona

I'm not interested in PTFE fortified- or enhanced engine oils; I'm totally convinced that PTFE shouldn't be added to motor oil. My question was about the usefulness or uselessness of PTFE in gear oils, liquid multi-purpose lubricants (household-, gun-, specialty(?)- oils...) and greases.

PS: I thought I originally posted this question in the General- and Off Topic section??
I tried to edit the first post to eliminate some typos, using the editing tip found in the Edit function work-around sticky, but all I got was a second post. Any suggestions what I did wrong?

Thanks, Frank

 

[Tempest]

This is from Molakule, a lubrication engineer that used to post here often:

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PTFE does gel and should never be used as an EP additive since it shears.

In addition, no one has ever proven that PTFE in particulate form adheres to metal.

PTFE is good as a grease thickener and reduces gear train noise in gear lubes.

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Link

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once used a PTFE fortified light grease -marketed as a gun specific product- of a well known brand for a while with very good results but stopped using it after I got some serious issues with corrosion.

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Mil-comm?

Quote:

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What about the asperities-filling claims

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I would also like to know about this one.

 

[JAG]

I think he said it's not for use in engine oil. My engineering handbook mentions PTFE based lubricants so it must be useful in some applications. I don't have the book with me right now so can't look it up. I think it said it doesn't have the high load carrying capability that MoS2 and graphite have so it's probably best in low load situations where the PTFE particles would act as soft ball bearings and not be totally overwhelmed (flattened/torn up) by the loads. I don't think the PTFE does not have to bond to the metals to be useful.

You mentioned use in gear oils. If you mean car gears, I think the loads would be too large for the PTFE particles to help much if at all.

MoS2 works well in many applications (except when temps exceed something like 750C degrees) so why not use that instead?

 

[bruce381]

PTFE will NOT wet or plate out on Oily metal It will do no good other than clog things up.


If you wanted to add something that will burnish into metal asperities try a Moly disulfide or even to some degree graphite.

They are the most common solid film lube additive added to gear oils.


bruce

 

[Mystic]

For cleaning an engine I believe in Auto-RX. For making a transmission work longer and last longer I still believe in Lubegard products. And there is a Lubegard product that works in engines. I don't think PTFE belongs in engines. And I don't believe Moly belongs in engines unless it is the proper chemical combination containing Moly. There used to be products that contained lots of Moly but did not work. They had the right idea but needed proper chemistry. Now a lot of motor oils contain Moly and work properly.

I doubt if PTFE will work any better in engines than the Moly that is being added today to many motor oils. And that Moly has the proper chemistry. In fact, I can think of one company that was selling a product that contained PTFE that later on said that they had improved their product by also adding Moly.

I think it is a good idea to stick to the excellent motor oils of today, use Auto-RX for cleaning, and maybe some Lubegard in automatic transmissions and Lubegard power steering supplement in power steering units.

 

[CluelessFrank]

Thanks for the replies

I'm aware of the benefits of using MoS2 in lubricants; the concept is well understandable and time-proven.

My question is only about the possible benefits or disadvantages of using PTFE suspended (not the fluorinated lubricants like Krytox, Halovac, etc.) in non engine-specific (no motor oils) lubrication applications (other possible attributes like thread-sealing etc. are of no interest), so called dry lubes excluded.
I don't want to add or use PTFE in a lubricant formulation myself; I'm just curious about the current wisdom.

Could we suspect that the main lubricating properties of a PTFE-containing liquid lubricant come from the base formulation and there wouldn't probably be much of a difference when the PTFE would be left out of the brew altogether?

Tempest:
I read through Molakule's explanations and they make sense to me. Many years ago, I discussed lubes suitable for guns with a Klüber engineer and the man almost had a fit when the discussion came to PTFE fortified liquid lubes -especially for-, but not limited to gun applications- which he regarded as utter #@$%!; he told me that using PTFE would only make sense in paste- or grease form because of the suspension problem and that Klüber at the time (then...), mainly because the market demanded it, would be about to release a great Teflon fortified grease. However, as he stated himself, he had no clue about gun technology and was convinced that PTFE would pyrolyse in a gun barrel and the resulting HF would attack the steel; I think at least this last assumption proved to be wrong regarding the decade long use of PTFE lubes in gun barrels with no known ill effects on the steel.

Quote:

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Mil-comm??

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No.

JAG:

Quote:

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...where the PTFE particles would act as soft ball bearings and not be totally overwhelmed (flattened/torn up) by the loads.

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I could think of the solid PTFE filler exerting some buffering action by giving some body to a grease or paste, but what about its use in liquid lubes?


bruce381:

Quote:

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PTFE will NOT wet or plate out on Oily metal

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...that's how I understand it, too; then, the claimed filling of the metal's asperities would be purely coincidental, working in a wash-in, wash-out manner, so to speak? Manufacturers always talk about the PTFE adhering to- and coating metals; I wonder how they would achieve the necessary surface activity of the PTFE?

Any thoughts about the fumed silica, not only when used as a grease thickener but as a suspension-matrix for PTFE in oils, too? Any negative assumptions?

Mystic:
Yes, I know about some lubes -not only engine lubes- combining PTFE and Moly. Being convinced about the benefits of Moly in one- or the other lubricant-specific form, I'm still wondering about the benefits of PTFE.

Thanks, Frank

 

[Tempest]

Not Mil-comm...hmmmm...care to share??

I have read that PTFE will shear with loads as low as 150psi. This is nothing in autos, and I would imagine that this would be easily reached by asperity contacts in firearms. I agree with your Klüber engineer that PTFE is mostly a marketing gimmick.

I thought for awhile about the "micro-ball bearing" theory as well, but when you consider that the metal surface is in fact rougher than the size of the PTFE, it just doesn't workout.

 

[JAG]

Quote:

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I thought for awhile about the "micro-ball bearing" theory as well, but when you consider that the metal surface is in fact rougher than the size of the PTFE, it just doesn't workout.

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I think there would have to be several layers of particles to overcome the asperities, and I agree that just having a "ball here and a ball there" wouldn't do it unless the surface finish was super smooth which is usually not the case. So there would have to be a high enough concentration of teflon for it to help which would depend on the surface roughness. I wish I had my engineering handbook here at work...I just took it home 2 nights ago...bad timing! Without it I don't know what else to say. See if you (original poster) can track down an engineering book and see for yourself where PTFE works well and where it doesn't.

 

[bruce381]

""Any thoughts about the fumed silica, not only when used as a grease thickener but as a suspension-matrix for PTFE in oils, too? Any negative assumptions?""

Commonly used to gell and also hold in suspension solid lubricants such as Moly and graphite aswell as PTFE has no negitive of hand that I can think of.
bruce

 

[fitzz47]

all you need to know
http://www.dupont.com/lubricants/en/faqs.html

 

[Mystic]

I would not use PTFE containing lubricants on a gun either. I have a training video from a guy who builds super quality guns, is a expert marksman, and even sells his own brand of gun oils, gun cleaners, and gun greases. He tested various gun oils and a typical ordinary gun oil proved superior to a PTFE containing gun oil in his testing.

I am not really very impressed with any gun oil but the best gun oil I have ever foud is a synthetic gun oil called MPro7. I am sure that the Hoppes Elite gun oil is the same thing. The best cleaner I ever found was MPro7 cleaner. The Hoppes Elite cleaner is the same I am sure.

This is not a post on gun lubricants, but since the subject came up. I have tried PTFE containing gun lubricants and as far as I am concerned a person would be just as well off using Hoppes ordinary gun oil.

PTFE might be great in greases. I don't know. But I will never again use a PTFE containing product in engine oil. I once did use such a product (not Slick50 but another one) but I will never use such a product again. Modern motor oils that contain Moly in a chemical form are probably BETTER than PTFE products, will not potentially damage your engine like those products might, and you don't have to pay extra for the Moly. I will not use PTFE in a gun oil. I know a woman who is a pretty good shot who swears by the PTFE gun oil that she uses, but I tried her gun oil and I will not use it. Now PTFE in a grease might be great but I don't know about that.

I used to be interested in every oil supplement for engines that came along although I tried only a few. The list of stuff I will use today is pretty short. The only product I use in engine oil is Auto-RX. It worked for me. I don't even use Lubegard engine supplement because it is too expensive for every oil change although I still have faith in Lubegard products. If I had an automatic transmission I would use Lubegard transmission supplement. And if my power steering unit was making noise in the cold I would use Lubegard power steering supplement. There is not a whole lot of other stuff I will use-Bar's Leak, Regain Fuel System Cleaner, and that is about it.

If a person uses good quality engine oil (especially if you use a synthetic), good quality transmission fluid, etc., you could probably run a car or truck a very long way with no supplements at all, not even Auto-RX. But I think Auto-RX will help keep the engine clean. And you may have a need for a particular product depending on what happens along the way.

I am not an expert on lubricants, but I think the best advice is to avoid PTFE containing products for engine oils (and for guns too, for that matter).

 

[fitzz47]

I used to take tubes of Krytox grease with me to Nascar races when I worked for Dupont.The teams loved the stuff,said they never had a axle break using this stuff.$220 a tube ten years ago.

 

[JAG]

Go to the links on here that apply to this subject:
http://www.engineersedge.com/lubrication/lubrication_knowledge_menu.shtml

 

[Big Jim]

Maybe Volvo has special knowledge on this subject. Their disc brake caliper grease is labeled as PTFE Silicon grease. I suspect that it is actually ATE supplied since it seems to match what I have often seen as original caliper slide pin grease on ATE calipers.

I really like the stuff. I use it on disc brake caliper slide pins even if I use other lubricant elsewhere on the caliper. It is extremely slippery.

 

[CluelessFrank]

Thanks a lot for the great replies!


Tempest

Quote:

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Not Mil-comm...hmmmm...care to share??

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Yes, but not on a public forum...

Quote:

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I thought for awhile about the "micro-ball bearing" theory as well, but when you consider that the metal surface is in fact rougher than the size of the PTFE, it just doesn't workout.

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Thought the same way, too. There's the claim that the (tailor made?...) PTFE particles would actually pack tightly together into the asperities like snowballs, thus filling them up and creating a smooth surface to help maintaining a lubricating film between the opposing surfaces. On the other hand, those same particles should neither clog together nor accumulate where- or blocking whatever they shouldn't. Intelligent technology, maybe?

(*)

JAG

Quote:

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...track down an engineering book and see for yourself where PTFE works well and where it doesn't.

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I remember reading recommendations regarding PTFE containing greases or pastes for some specific applications. Did you see liquid lubes containing solid PTFE particles recommended in an engineering book?

Thanks for the link to the engineers edge! Very informative short descriptions; however, not much about the theory how the asperity-filling concept would work using PTFE solids in grease or oil. I thought the transfer film formation concept also mentioned there would apply only to solid PTFE surfaces rubbing against rough counter surfaces, but here's a quote from an explanation I found on Acheson's website; see links at the bottom, too:

Quote:

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(*)PTFE solid lubricant additives are soft, waxy, slippery, opaquewhite, thermoplastic polymers which have an extremely low coefficient of friction. They function by smearing a deposit on the surface, thereby separating the surfaces and reducing friction.

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Bruce381
From what I've just read about solid additives on the quoted Acheson site, one could then suspect that the need for using fumed silica (or any other suitable substance) to keep the PTFE (or other-) particles in suspension (not for thickening- or gelling purposes) would be primarily dependent on particle properties like size and surface treatment (stabilizing...(?)...), so there would probably be no need to use fumed silica with very finely dispersed or colloidal particles. On the other hand, fumed silica is also used as thickener -like you already stated- only in grease formulations without the adding of other solids.


fitzz47
Thanks for the DuPont link, I visited this site before but wasn't able to find more in-depth explanations regarding the exact working mechanism of solid PTFE particles. The Krytox lubricants sound interesting, though.

Mystic

Quote:

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I would not use PTFE containing lubricants on a gun either.

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I have no intention of doing this(again...), too. My question wasn't primarily about gun lubes; I just mentioned the experience I had with a specific product: excellent lubricity, especially on trigger mechanisms, but some disturbing incidents with corrosion. Generally, I too was never overly impressed by PTFE-ed gun lubes and tend to attribute the performance features to the base fluid and other additives rather, but who knows?... Besides, wherever suitable, I prefer using oil over grease on guns.

BigJim
I think I heard about this caliper lube used by Volvo; is this a reddish colored paste? I think they used Plastilube before, which is still used by BMW and VW/AUDI, I think?



Some other quotes from the Acheson site. You may find it interesting that they sell their PTFE solid additives (and other solids) for engine oil applications,too, something DuPont does not endorse.

Quote:

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Acheson's colloidal dispersions are sufficiently fine to pass through standard automotive filters and will operate satisfactorily in automatic lubricators and other close fitting mechanisms without clogging or buildup . The particles in these dispersions are smaller than blood cells and invisible to the naked eye.

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Quote:

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Regardless of particle size, even the finest dispersion will settle if it is not stable. When dispersions are not stable, they will flocculate, that is the fine particles will agglomerate into large particles, and quickly settle. This can be prevented by coating theprimary particles with a layer of stabilizer whichdiscourages agglomeration. A properly designed stabilizer is an essential partner to a fine particle size dispersion.

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http://www.achesonindustries.com
http://www.achesonindustries.com/process_lubricants/lubeadddata.asp



It's not clear to me how solid PTFE particles should be able to get smeared into asperities and, at the same time, not be able to clog-, agglomerate and -or accumulate. If the particles can indeed be smeared (=pressed into agglomerates, larger formations) into asperities under pressure, then couldn't they as well be pressed into machining marks and larger crevices and then those larger "pressed together" particles could come free again and migrate through the lubricant until they settle elsewhere, probably clogging some structures???

Frank

 

[Big Jim]

Currrently the Volvo disc brake caliper lube is white. Earlier it was slightly pink. Same part number on the tube.

 

[dwendt44]

Teflon, in it's pure state, is white.