Why Castor?

[AlisoBob]

CASTOR OIL
By Bert Striegler.


Back in 1983 there was quite a controversy in magazines about the tests that were necessary to measure the "lubricity" of various oils that might be useful in engines. Castor oil was used as the benchmark, but it was obvious no one knew why this was so. They apparently got a lot of info on various industry tests of lubricants, but these were really designed for other purposes. This was my answer. I will remind you that I was a lubrication engineer and not a chemist, but I drew my chemical info from Bob Durr, the most experienced lubricant scientist in the labs at Conoco.

Bob worked with my group on many product development projects and I can tell you that he is one smart hombre! Small changes were made in the text, but surprisingly very little has really changed since this was originally written. Here goes with the answer:

"I thought I would answer your plea for more information on castor oil and its "film strength", which can be a very misleading term. I have never really seen a satisfactory way to measure the film strength of an oil like castor oil. We routinely use tests like the Falex test, the Timken test or the Shell 4-ball test, but these are primarily designed to measure the effect of chemical extreme pressure agents such as are used in gear oils. These "EP" agents have no function in an IC engine, particularly the two-stroke model engine types.

You really have to go back to the basics of lubrication to get a better handle on what happens in a engine. For any fluid to act as a lubricant, it must first be "polar" enough to wet the moving surfaces. Next, it must have a high resistance to surface boiling and vaporization at the temperatures encountered. Ideally the fluid should have "oiliness", which is difficult to measure but generally requires a rather large molecular structure. Even water can be a good lubricant under the right conditions.

Castor oil meets these rather simple requirements in an engine, with only one really severe drawback in that it is thermally unstable. This unusual instability is the thing that lets castor oil lubricate at temperatures well beyond those at which most synthetics will work.

Castor oil is roughly 87% triglyceride of ricinoleic acid, [ (CH3(CH2)5CH(OH)CH2CH=CH(CH2)7COO)3(OC)3H5 ], which is unique because there is a double bond in the 9th position and a hydroxyl in the 11th position. As the temperature goes up, it loses one molecule of water and becomes a "drying" oil. Another look at the molecule. Castor oil has excellent storage stability at room temperatures, but it polymerizes rapidly as the temperature goes up. As it polymerizes, it forms ever-heavier "oils" that are rich in esters. These esters do not even begin to decompose until the temperature hits about 650 degrees F (343 deg C). Castor oil forms huge molecular structures at these elevated temperatures - in other words, as the temperature goes up, the castor oil exposed to these temperatures responds by becoming an even better lubricant!

Unfortunately, the end byproduct of this process is what we refer to as "varnish." So, you can't have everything, but you can come close by running a mixture of castor oil with polyalkylene glycol like Union Carbide's UCON, or their MA 731. This mixture has some synergistic properties, or better properties than either product had alone. As an interesting sidelight, castor oil can be stabilized to a degree by the addition of Vitamin E (Tocopherol) in small quantities, but if you make it too stable it would no longer offer the unusual high temperature protection that it did before.

Castor oil is not normally soluble in ordinary petroleum oils, but if you polymerize it for several hours at 300 degrees F (149 deg C), the polymerized oil becomes soluble. Hydrogenation achieves somewhat the same effect.

Castor oil has other unique properties. It is highly polar and has a great affinity for metal surfaces.

It has a flash point of only 445 degrees F (229 deg C), but its fire point is about 840 degrees F (449 deg C)! This is very unusual behavior if you consider that polyalkylene glycols flash at about 350-400 degrees F (176-204 deg C)and have a fire point of only about 550 degrees F (288 deg C), or slightly higher.

Nearly all of the common synthetics that we use burn in the combustion chamber if you get off too lean.

Castor oil does not, because it is busily forming more and more complex polymers as the temperature goes up. Most synthetics boil on the cylinder walls at temperatures slightly above their flash point. The same activity can take place in the wrist pin area, depending on engine design.

Synthetics also have another interesting feature - they would like to return to the materials from which they were made, usually things like ethylene oxide, complex alcohols, or other less suitable lubricants. This happens very rapidly when a critical temperature is reached. We call this phenomena "unzippering" for obvious reasons.

So, you have a choice. Run the engine too lean and it gets too hot. The synthetic burns or simply vaporizes, but castor oil decomposes into a soft varnish and a series of ester groups that still have powerful lubricity.

Good reason for a mix of the two lubricants! ( " 927 " is a mix as described here!)

In spite of all this, the synthetics are still excellent lubricants if you know their limitations and work within those limits. Used properly, engine life will be good with either product. Cooked on a lean run, castor oil will win every time. A mix of the two can give the best of both worlds.

Like most things in this old life, lubricants are always a compromise of good and bad properties. Synthetics yield a clean engine, while castor oil yields a dirty engine, but at least now you know why! "

Bert Striegler

Bert was the Sr. Research Eng'r. (ret.) at Conoco Oil Co.

[M.F.D.B.]

Ahh, the good 'ol Bobby cut-n-paiste!! Now I feel at home!! HAHA

[britincali]

Its worth it for the smell alone.

[M.F.D.B.]

WTF 180 already!! HOLLY SHEEIT!!

[AlisoBob]

Ahh, the good 'ol Bobby cut-n-paiste!! Now I feel at home!! HAHA

"F" and "J" are the ones that KICK ASS!!!!

[M.F.D.B.]

Ahh, the good 'ol Bobby cut-n-paiste!! Now I feel at home!! HAHA

"F" and "J" are the ones that KICK ASS!!!!

Must be using a MAC...

[AlisoBob]

Naaaaaaa.... just type shitty.....

[ou812]

one note on castor, if you live in a cold climate , bring the bottle in the house over the winter, once it gets to zero (32dg.) it is toast and should not be used.

[M.F.D.B.]

Nah, still works good as a laxative...HAHA

[britincali]

one note on castor, if you live in a cold climate , bring the bottle in the house over the winter, once it gets to zero (32dg.) it is toast and should not be used.

Why what happens to it?

[M.F.D.B.]

It lets the funk out?? My bike needs BOOKOO funk to stay running...

[AlisoBob]

It will seperate from gas at cold temps.... But I never heard of unmixed Castor going bad...


Explain your thoughts?

[MICK]

But what if my engine doesn't see temps high enough to break synthetics down in the first place? Does the Castor do me alot of good? This reminds me of Evans coolant. If I never boil my bike over, what good is useing NPG-R and seeing higher running temps because of it?

[AlisoBob]

Its not the temps the engine is, its the temp that combustion is occuring at...

Castor excels at every lube test parameter..except gum.

Synthetics lube o.k.....cleanliness is their game.

'927 is a Castor / Synthetic Blend...

Best of both worlds...

[ou812]

The front label reads as follow's " Castrol Racing A747 2 cycle oil, Not to be exposed to tempertures below 0c.

My understanding from 250 TZ and RS riders is it is the best oil period for the application they need but with the following drawbacks.

1) Only stays truely mixed for 6 to 8 hours, re shaking after does not truely remix it.

2) It loves to absorbs water , one must flush the motor or run with other premix after the last race to advoid rust.

3) It lowers octane levels more then most premixes.

4) Storage of the bottle below zero will ruin the oil.

I do not know the chemical reason why cold ruins it , but I do know it's a big no no with those guy's

So I am of the belief the all hi grade castors will be suffer from zero degree exposure. Possibly to a lesser extent with a blend like 927, but I'm not about to gamble, best to put any castor or castor blend inside for the winter.

[AlisoBob]

Direct from Blendzall:



From: blendzall
Date: Mon Jun 25, 2007 6:37:19 AM US/Pacific
To: Higginson
Subject: Re: Storing Castor OIl



Hi Bob, Thanks for the questions regarding our product.


No, that is NOT true! I don't know if you are talking about pure castor oil or the oil that we make, but it sholdnt matter. I dont know of any issues with either product. They dont know what they are speaking of, and are probably just repeating a rumor.

It does not matter what temp it is stored at. As long as you put the lid on tight, it should keep for quite a long time.

Let me know if you have any more questions.



Regards,

Phyllis

-------------- Original message from Higginson : --------------


> I was told that storing Castor Oil in cold tempatures will ruin it, and
> it should never be exposed to anything else but room temps..
>
> Is this true?
>
> Thanks
>
>
> Bob
>

[ou812]

should never be exposed to anything else but room temps..

I contacted Castrol and several A747 users about this lets see where it goes, but room temp many have partly caused the reply. But I can't for the life of me see why such a caution would be printed on the front lable if the warning was not true.

[AlisoBob]

Post up what you find out...

[ou812]

http://www.sciencelab.com/xMSDS-Castor_oil-9927126

Here's what I've found so far, see section 7. I will get something out of Castrol. But I would say this does have some weight.

[Spanky]

ou812, not to dis you or anything, but I was a refrigeration engineer for 18 years. Most refrigerant oils are approximately 80% castor and 20% blending agent. Even in a high-temperature application (a walk-in cooler for example) The oil inside the system will be exposed to temperatures as low as 70-80 degrees below zero farenheit as the refrigerant evaporates inside the evaporator coil. If castor oil were somehow damaged by low temps, this would certainly do it, yet I've never seen any indication that this is so.

[M.F.D.B.]

Thats pretty damaging holmes...

[AlisoBob]

Looks like standard "boilerplate" text to me.... I think any liquid storage MSDS sheet says" Keep from freezing" to guard against vessel rupture.

It has nothing to do with compound conditioning...

[M.F.D.B.]

Guess im safe to go back to making my laxative popsickles Bobby??

Funny thing I noticed in my research "Castor Oil WILL NOT FREEZE"...So why would exposing it to freezing temps change anything??

[ou812]

yes but our topic has to do with mixing with gas, my understanding is once frozen it will not mix with gas in a correct fashion again. The sheet posted was just something I came across. Hold on till I hear from Castrol. The question would still stand Why would they place that warning if it does not apply?

[97af]

one note on castor, if you live in a cold climate , bring the bottle in the house over the winter, once it gets to zero (32dg.) it is toast and should not be used.

I mixed up 5 gallons last weekend with a new bottle that I found in trucks toolbox.It had been in there since last October of 06. Over the winter,we had sustained low temps in the -20 range. No melt downs in my boys KTM or either of my CR's that were ridden. I'm glad that bottle of 927 wasnt toast.......