cylinder oils are a family of specialty oils that were originally formulated
about 150 years ago to lubricate the moving parts within the valve chests and
cylinders of reciprocating steam engines. Early steam engine operators quickly
learned that their machines required some form of lubrication. They discovered
that beef tallow, a component of early hand made soaps, was an excellent
lubricant when introduced into the valve chests of their engines. Unfortunately,
tallow has an undesirable characteristic though. The early tallows were full of
free fatty acids that form corrosive acids when decomposed in the presence of
steam. These acids attacked the metal parts of steam engines.
Drake discovered oil in Pennsylvania in 1859 the introduction of refined mineral
oils as less expensive and better lubricants rapidly followed the development of
the modern petroleum industry. Early refineries used simple distillation towers
to separate out different crude oil fractions such as kerosene, light
lubricating oils and heavy lubricating oils. It was found that the residuum at
the bottom of the distillation towers formed an excellent lubricating film in
hot steam cylinders. This residue became known as "cylinder stock" and has been
called this name ever since. Further refining cylinder stock produces more
desirable characteristics and a whole series of heavy, high viscosity products
is extracted from the basic cylinder stocks.
|It is important to note here that the crude oils produced from
the fields in Pennsylvania, New York, Ohio and West Virginia have peculiar
characteristics that are unique in the oil industry. They are "paraffinic" crude
oils that have many desirable characteristics as lubricating oils. They are
particularly desirable for steam cylinder oils because they exhibit the greatest
stability in high temperature applications and change viscosity less per degree
of temperature change than "asphalt" based crude oils. When asphalt based crude
oils are distilled heavy tarry residuum is found at the bottom of the
distillation towers and this residue is typically used to make asphalt for road
paving and roofing tars.
Therefore, the best cylinder oils have always been
made from "Pennsylvania Grade Crude Oil". Green Velvet Steam Cylinder Oil*
is manufactured from pure Pennsylvania Grade base stocks that come from local
fields in Pennsylvania, New York, Ohio and West Virginia.
The use of heavy mineral oils in steam engine cylinder lubrication was
quickly found to be less than perfect because, unlike tallow, mineral oils will
not mix with water. In steam engine cylinders using saturated steam large
quantities of condensed steam form water droplets that move at high velocities
with the rapidly traveling steam throughout the engine passages. This condensate
constantly washes the rubbing surfaces and does not allow the oil to establish a
stable, long lasting lubricating film. Nineteenth century engine operators found
that they had to feed large quantities of mineral oil to get reasonable
performance out of the new oils. Experimentation proved if a small amount of
tallow (or some other animal fat such as lard oil or sperm oil) was mixed with
the mineral oils a nice compromise was formed. The tallow "saponifies", or forms
a sticky, soapy emulsion when heated by the steam and agitated by the turbulence
in the cylinders and valve chests. The mineral oil gets caught up in this
emulsion and, in effect, a crude grease is formed where the soapy emulsion
"holds" the oil against the cylinder walls and other rubbing surfaces.
The result is a "compounded" oil that will "wet", or spread over all the
rubbing surfaces and resist the washing effect of water droplets in the steam.
This is analogous to washing your hands with soap. The soapy emulsion helps
"wet" your hands, cut through the natural oils and lift impurities from the
skin. It was quickly found that only a small amount of tallow was needed to form
adequate emulsions and today’s compounded oils generally use 10% or less
compounding. The small amount of tallow in the oil significantly reduced the
amount of corrosion found when 100% tallow was used for lubrication prior to the
introduction of mineral oils. Yet, it was enough to help significantly reduce
the amount of oil required to lubricate saturated steam cylinders.
Tallow is produced as a byproduct of animal carcass rendering and this
industry has evolved refining processes that have gradually produced better beef
tallows for cylinder oil compounding. The primary improvements have removed most
of the corrosive free fatty acids and today’s tallow products have almost
eliminated this component entirely.
Green Velvet Steam Cylinder Oil* compounding is fortified with a synthetic
copolymer known as a "tackifier". This is a modern, non-toxic, non-hazardous
additive that helps stabilize the emulsions in hot applications and improves the
"tackiness" of the oil. Both the compounding and tackifier are excellent
lubricants by themselves and both components help improve the lubricity of the
base mineral oil stocks.
Specifications - How they evolved
Today, most lubricating oils are manufactured in compliance with
some type of standard specification. In many cases specifications are generic
and are developed by an association that is formed by the manufacturers of the
machinery lubricated by a specific type of oil or grease. The Society of
Automotive Engineers (SAE) is such an association. It is familiar to everyone
who uses motor oil in automobile engines.
Steam cylinder oils have never been formulated to a standard specification
that has been agreed upon by a consortium of steam engine manufacturers. It is a
curious mystery of history that such a specification was never developed, but
the stubborn independence of early American industrialists is probably mostly to
blame. However, the Skinner Engine Company developed generic guidelines for
steam cylinder lubricants applicable to their line of steam engines. Skinner was
the last of the steam engine builders and built their last unaflow steam engine
in 1983. (Their guidelines are the best available and Green Velvet Steam
Cylinder Oils* are based on the Skinner recommendations.)
One of the significant generic lubricant specifications is the heavy gear oil
specifications developed by the American Gear Manufacturer’s Association (AGMA)
over 50 years ago. Many gear drives require a heavy, viscous lubricant.
Additionally, when water or moisture is present some type of animal fat
compounding is necessary to prevent the heavy lubricant from washing off the
sliding gear surfaces. It was found that compounded steam cylinder lubricants
also made excellent gear lubricants.
Over the last 50 years the gradual demise of steam engines in all types of
service has shrunk the steam cylinder oil market to a pitiful remnant of its
original proportions. This has caused most specialty blenders that specialized
in steam engine lubricants to go out of business. Today the major oil companies
and one or two specialty blenders are the only makers of steam cylinder oils and
this business is a small fraction of their total lubrication operations. Indeed,
many of these oil companies have discontinued, or are in the process of
discontinuing their cylinder oil product lines.
More importantly, the only identifiable commercial market that really remains
for steam cylinder oils is for gearbox lubrication. Almost all the major oil
companies have stopped calling these lubricants cylinder oils and now advertise
them as gear oils. Their specifications all claim compliance with the AGMA
specifications and their product designations call out the appropriate AGMA
specification number. The primary differences between gear lubrication service
and steam cylinder lubrication service are the lower temperatures found in gear
boxes and the requirement that enclosed gearboxes re-circulate the lubricant
many times for extended periods before change out. In steam cylinders the oil is
applied once then is replaced as more is required to maintain adequate
The improvement in lubrication technology and chemistry has evolved many
chemical additives that improve the stability and life of lubricants in
re-circulating service. Gear lubricants are no exception and most gear oils have
additives such as oxidation inhibitors, rust inhibitors and viscosity improvers.
While these additives improve the lubricant’s performance in gearboxes they are
not stable at elevated temperatures and tend to come out of the oil as
undesirable deposits in hot steam cylinders. In extreme cases where viscosity
improvers have been added the base oils fail completely in steam cylinder
It is difficult to serve two masters and steam engine operators should be
aware that most of the gear oils available as steam cylinder lubes are not being
manufactured for steam cylinder service even though many specifications still
call out steam cylinder lubrication as an appropriate application. This does not
mean that these lubricants will not work in steam cylinders, but most
lubrication engineering offices have no steam engine lubrication experience any
more and there are almost no lubrication engineers who can assist with steam
cylinder lubrication applications.
Green Velvet Steam Cylinder Oil* was developed to fill this widening gap.
While industrial steam engine applications have all but disappeared there is a
vigorous heritage and recreational steam engine industry that is struggling to
find true steam cylinder oils that are blended specifically for steam engine
service. Green Velvet* blending formulations and specifications are not intended
to fulfill any type of gear oil requirement and are manufactured exclusively for
steam engine service. The oil components are obtained from traditional sources
and the specifications are developed from the traditional recommendations the
Skinner Engine Company engineers found worked the best. Therefore, Green Velvet
Steam Cylinder Oil is a simple steam cylinder oil that predates most of the
"improved" gear oils that are now being used. Furthermore, Green Velvet is
available to end users in 1 pint, 1 quart, 1 gallon, 5 gallon and 50 gallon
containers. Whether end users need a lot of oil or a very small amount, Green
Velvet has a container size to fit everyone’s needs.
Specifications - How to read them
Green Velvet Steam Cylinder Oil specifications are based on formulations that
are generally not published and are retained as trade secrets.
Because steam cylinder oils have never been manufactured to a standard
generic specification that is published there are a wide range of cylinder oils
that create confusion when the proper type of oil is being sought for a
particular application. Additionally, major oil companies tend to change
ingredients without notice because their lubrication operations utilize
byproducts from their primary fuel making refineries. Sometimes such changes
cause problems in steam cylinders and end users get blindsided because these
changes come without any notice or warning.
In an effort to standardize formulations and reduce confusion, Green Velvet
lists all ingredients in its oils, identifies formulations with a formula
designation like Formula 1 or Formula 2 and tabulates a standard set of
specifications across all oil types. Green Velvet specifications also contain
some general application guidelines to help determine which oil type is
appropriate for different heritage and recreation steam engine applications.
Finally, Green Velvet’s developer, William Petitjean, P.E. has over 40 years
experience with steam engines and he is happy to discuss applications with end
There are nine specification parameters listed for all Green Velvet Steam
Cylinder oils. They are explained below.
- Base Oil: The base oil is the dominant component in cylinder oil and
generally makes up 90% or more of the final product. The viscosity and
lubricating characteristics of the base oil represent these characteristics in
the final product. Choice of the proper base oil is a key part of manufacturing
good quality steam cylinder oils.
- Compounding: The amount of compounding is listed as a percent by volume
of the total product. The amount of compounding determines how resistant the oil
is to water washing and determines the amount of emulsion that is generated in
the valve chest and steam cylinder. More compounding improves an oil’s "wetting
ability", or its ability to spread evenly across rubbing surfaces in the
presence of water. Green Velvet Steam Cylinder Oil uses a maximum of 10%
compounding. This compounding is formulated especially for steam cylinders.
- Tackifier: The synthetic copolymer tackifier is identified as an
additive so Green Velvet customers know every ingredient in their oil. There are
no mystery ingredients in Green Velvet Steam Cylinder Oils to gum up customers’
- % Compounding: This is the percentage of the total product volume that
is made up of compounding. This is an important parameter to list because it
helps determine which engine applications are appropriate for a particular oil.
The basis for application is steam pressure, temperature, engine type, engine
size and load factor.
- Color: The color is a perceptive parameter that helps identify steam
cylinder oil by color and texture when oil cans and lubricators are being filled
with different oils. Steam cylinder oil is traditionally a green opaque color.
Engine bearing oils are generally a more neutral translucent or tan color. This
helps prevent putting the wrong oil in a lubricator. Green Velvet Steam Cylinder
Oil is the traditional dark green color in all its grades.
- Viscosity: This is a measurement of how "fluid" a liquid is at a
particular temperature. It determines how much "body" or film building capacity
the oil has at the high temperatures prevailing inside steam cylinders. The
higher the viscosity the higher the ability to build stable films that withstand
high pressures, high temperatures and the scuffing of heavy, fast moving parts
inside the valve chests and cylinders. As a general rule, the lowest possible
viscosity should be used in each application. This rule allows the easiest
handling of heavy oils, improves atomization and application of oil into the
steam circuit and builds films that are stable enough to adequately lubricate
the moving parts at the conditions prevailing in a particular application. Two
viscosity units are listed. SUS (Saybolt Universal Seconds) is an older unit
that can be found in many older oil specifications. Centistokes is a more modern
unit that is used more frequently today. 210º F is nearly equal to 100º C.
- Flash Point: This is the temperature where the vapors driven from a
heated sample of cylinder oil will "flash" into flame, but will not support a
continuous burn. A continuous burn of vapors is called the Fire Point. This
"flash" test is performed according to the American Society of Testing Materials
(ASTM) Test Protocol D-92. This is a comparative parameter that helps determine
how much a particular cylinder oil can resist the vaporizing effects of high
steam temperatures. The higher the flash point the more resistant the oil is to
evaporation that destroys its ability to build a stable lubricating film on the
- Carbon Residue: This is the amount of carbon residue that remains after
a sample of cylinder oil has been heated to a high temperature that evaporates
and burns all components except a carbon residue that is left at the bottom of
the test cup. The final amount of residue is listed as a percentage of the total
weight of the original sample. The test is performed according to the ASTM Test
Protocol D-189 and is called the Conradson Carbon Residue. This parameter helps
determine how well the base oils are refined and also helps determine which
additives contribute to the overall carbon residue content. Low carbon residue
numbers below 2% are desirable because they indicate the oil will not
precipitate as much hard or gummy deposits in the lubricators, valve chests and
cylinders. Another test called the Ramsbottom test is also sometimes used. This
test uses carbon residue as a percentage of the total sample weight too. But,
the test protocol is different and Ramsbottom numbers are lower than comparable
Conradson numbers. Always ask for the test type before interpreting carbon
The above explanations of the specification parameters for Green Velvet Steam
Cylinder Oil are intended to give a better understanding of their use in
defining good cylinder oils and helping choose the correct lubricant for a
particular application. There are many good sources of information for those who
wish to learn more about these parameters. Finally, the best criteria of a good
cylinder oil is in its performance because so many different conditions exist in
steam engine lubrication it is impossible to be very precise about which oil is
The Green Velvet Steam Cylinder Oil organization is always interested in
customer feedback that helps further perfect the oil offerings. This discussion
of specifications and how to read and understand them is a result of a customer
request. We strive to make Green Velvet Steam Cylinder Oils the preferred
lubricant for all steam engine operators.
*Green Velvet Steam Cylinder Oil (TM) is a
registered U.S. Trademark
©June, 2002 by Lubrication Specialties
For further information
P.O. Box 1010 Stearns,
KY 42647 USA
Tel. 606-376-3035 Fax 606-376-1212
Written by Bill Petitjean
Bill Petitjean's company:
is a distributor of Green Velvet Cylinder Oils*.