By Ed Newman
This article appeared in Power Stroke Registry,
Summer Edition 2003
AKING AND RECORDING MEASUREMENTS has been one of the
hallmarks of the Age of Enlightenment. It seems like modern people measure
everything. We have measures of time, such as weeks, hours, minutes,
and years. We have measures of mass, such as grams, pounds and tons.
We have measures of sound volume, of energy, of radioactivity, of pressure,
of type font sizes, of land mass, and of speed.
AUTOMOTIVE RELATED MEASUREMENTS
Horsepower, as you might guess, is the amount of power exerted by one
horse pulling. After many careful measurements James Watt, inventor
of the steam engine, determined that a horse can lift 550 pounds at
a rate of one foot per second, which translates into 745.7 watts. Some
clever American engineers decided that manpower should have a measurement
as well, equivalent to 0.1 horsepower or 74.57 watts.
MPG is the familiar acronym for miles per gallon, which
measures the rate of fuel consumption in a motor vehicle. One mile per
gallon equals approximately 0.4252 kilometers per liter. MPH is our
common measure of speed. One mile per hour equals 22/15ths feet per
second or 1.609 kilometers per hour or 0.447 meters per second.
RPM means revolutions per minute, a unit of frequency
as a measure of rotation rates in mechanics. In cars RPM is measured
by a tachomoter. Some motorists pay attention to RPM so they don't overrev
and cause component failure. Race car drivers try to keep RPM rates
in a range that will provide maximum power.
A quart as a unit of volume is so named because it represents
one quarter of a gallon. When measuring liquid, one quart is 32 fluid
ounces, or 57.75 cubic inches. On the other hand, when measuring dry
goods like pecans or blueberries, a quart is 67.201 cubic inches. Go
Drums are sometimes used for measuring oil, containing
55 U.S. gallons or about 208.198 liters. Drums are not the same as barrels,
the standard unit of volume for measuring crude. One drum is equivalent
to 1.3095 barrels. A barrel is equivalent to 42 U.S. gallons, which
is coincidentally the same size as a traditional wine barrel, more commonly
called a tierce.
But what about oil quality? What are the criteria that are important
when measuring the performance quality of a motor oil?
Part of the answer comes from understanding the role
that motor oils play when it comes to engine lubrication. Another part
of the answer comes from understanding that we live in a scientific
age in which nearly everything can be, and often has been, measured.
Knowing what to measure and how to measure it is an important part of
good decision making. We're talking motor oil here.
THE ROLE OF MOTOR OIL
Before we can discuss what makes a good motor oil, it
helps to understand what role motor oil actually plays in the performance
of an engine.
While motor oils serve a variety of functions, they
are primarily necessary to lubricate and to cool the engine. When the
engine is at rest, the motor oil sits in the bottom of the engine block
in what is called the oil pan. Upon start-up, an oil pump feeds oil
from the pan to the oil distribution system by means of a network of
passages, tubes, grooves and holes leading to the engine bearings and
other surfaces needing pressurized oil for lubrication. Other parts,
like the overhead valve system, receive a carefully controlled quantity
of non-pressurized oil through splashing or spray.
In addition to lubricating and cooling engine parts, motor oil must
allow easy starting, protect the engine from corrosion and oxidation,
keep the engine clean, form a tight seal between piston rings and cylinder
walls and help the engine use fuel efficiently.
In days gone by motor oil was made from the throwaway
byproducts of a barrel of crude oil after everything useful was taken
from it. In those early days the filter, if you had one at all, was
a by-pass type, filtering only a small percentage of the oil. In some
instance the filter was little more than a screen and the oil was changed
every five hundred or thousand miles. (Some of us recall grandpa's stories
of tires needing to be changed on every trip to town, the idea of longevity
being somewhat foreign back then.)
As cars and their engines became more sophisticated,
so too the requirements of a lubricant became increasingly demanding.
In the 1960's jet fighter pilots and their mechanics were becoming aware
of the advantages of synthetic oils, and a few of them experimented
with the notion of synthetic lubrication for automobiles. One of these
pilots, Lt. Colonel Albert J. Amatuzio, went further than the haphazard
experiments of his peers. His ten year quest resulted in the development
of AMSOIL, the first automotive synthetic motor oil to exceed the certification
requirements of the American Petroleum Institute (API).
SYNTHETIC VS. CONVENTIONAL PETROLEUM
Conventional lubricants are refined from crude oil which
has thousands of types of molecules. Refining is a process of physically
separating the impurities from the oil and further separating the light
and heavy components. Because refining separates products by weight,
it groups molecules of similar weight and dissimilar structure. The
result is a lubricant with a wide assortment of molecules. Some of the
substances in crude oil are detrimental to lubrication. Paraffins, for
example, are a common conventional oil contaminant that causes motor
oil to thicken in cold temperatures.
Synthetic motor oils are made from pure chemicals, not refined crude.
Their components are chemically reacted to produce finished products
with pre-designed performance characteristics. Because of their molecular
uniformity, they excel in reducing friction, which improves fuel efficiency,
controls heat and reduces wear. This molecular uniformity also helps
synthetics resist thinning in hot temperatures and thickening in cold.
MEASURES THAT MATTER
The American Society for Testing and Materials recognized
the need for uniform procedures that can be duplicated and verified
by laboratories in any location. The goal of establishing standards
is so important that the official publication of ASTM International
is called Standardization News.
Founded in 1898 and completely voluntary, ASTM is now
one of the largest non-profit standards development systems in the world.
The organization currently has 134 committees that write standardized
test methods for materials, products, systems and services. More than
8500 ASTM specifications have been established for products as diverse
as metal, paints, plastics, textiles, energy, consumer products, medical
services and instruments and even the environment.
Developing standard measurement methods is part of the
task of ASTM. Equally important is determining what measures are important,
tests that actually correspond to what the function of motor oil is
intended to fulfill. What follows here are some tests commonly used
to evaluate motor oil performance.
ASTM D-445 Kinematic Viscosity
The proper operation of equipment depends on the proper kinematic viscosity
of the oil at operating temperatures. Kinematic viscosity is a measure
of a liquid's flow under the influence of gravity. Some companies formulate
their lubes to tighter specs than others. One recent study revealed
that one in five off-the-shelf motor oils tested were outside the acceptable
performance range for their stated viscosities.
ASTM D-2270 Viscosity Index
This test indicates how much a lube's viscosity will change according
to changes in temperature from 40 degrees C and 100 degrees C. The higher
the viscosity index the better for motor oils that must perform in locations
with temperature variations.
ASTM D-5293 Cold Crank Simulator Apparent Viscosity
Cold crank viscosity affects the startability of engines in cold temperatures.
Low cold cranking viscosities make for easier cold cranking and more
dependable cold temperature starting, and less drain on batteries.
ASTM D-3829 Borderline Pumping Temperature
This test is used to predict the lowest temperature at which a motor
oil can be continuously and adequately supplied to an engine¹s
components. As the name suggests, the lower the temperature, the better
the oil circulates in cold weather. Synthetic oils are famed for the
extreme low temperature protection.
ASTM D-97 Pour Point
This test identifies the lowest temperature at which oil flows.
ASTM D-92 Flash Point and Fire Point
Flash point indicates the temperature at which a specimen vapors will
Flash point assesses the overall hazard of a material and is used in
shipping and safety regulations to define "flammable" and
"combustible" materials. Fire point measures the temperature
at which a specimen will remain burning for five seconds. Synthetic
lubricants with high flash and fire points are safer to use and transport
than petroleum lubes with lower ones. High flash point is indicative
of a greater high temperature operating range and better quality base
ASTM D-4683 High Temp, High Shear Viscosity
This test is representative of the conditions encountered in the bearings
of automotive engines in severe service. Lubricants with high scores,
such as premium synthetics, maintain their viscosity in high temperatures
after exposure to high shear. This means that they continue to protect
bearings even after exposure to severe service conditions.
ASTM D-892 Foaming Tendency
This test is important because of the turbulent environment in which
motor oils are required to perform. Foaming can lead to inadequate lubrication,
cavitation and mechanical failure.
ASTM D-4172B Four Ball Wear Test
The Four Ball Wear Test determines the relative wear prevention properties
of lubricants in sliding contact. The test involves three fixed balls
in a bath of lubricant with a fourth ball in rolling contact under pressure
at a specific level of severity. Wear protection is gauged by measuring
the wear scar that develops. A smaller wear scar means better protection
in typical engine operations.
ASTM D-5800 Noack Volatility
Oil volatility is the measure of how susceptible oil is to boil-off
under high heat conditions. Petroleum oils experience significant boil-off
during high temperature engine operation and subsequently higher oil
consumption. Evaporation loss contributes to damaging deposits, sticky
piston rings and oil blow-by, resulting in a drag on performance and
reduced engine life. Synthetic oils are far more impervious to this
kind of degradation. The lower volatility of synthetics is another reason
they are also better for the environment than conventional products.
SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure
- Type II
The Society of Automotive Engineers has devised a test to measure fuel
consumption and fuel economy. In a demonstration involving over-the-road
trucks an improvement of 8.2% was achieved by switching from conventional
lubes to synthetic lubricants (in this case AMSOIL products) in the
drivetrain and engine.
Here's an interesting, undisputed fact. By every one of these measures
premium synthetic motor oils are superior to conventional petroleum
motor oils. This truth is never even questioned by industry professionals.
So why, one might ask, isn't everyone using synthetic
motor oils and lubes? Here's one possible reason. To divert attention
away from the performance measures above the major oil companies focus
on one other measure: price.
Ironically, we live in an era in which people are spending more money
than ever on large vehicles or cool looking vehicles -- PT Cruisers,
SUVs, Hummers, and dualies. Insurance payments alone in most households
run ten times greater than motor oil costs. People are passionate about
their vehicles. How can they not be equally dedicated to protecting
their investment by using premium lubricants that promise longer life
to the object of their passion. You wouldn't expect price to be that
big of a deal, yet it is for some people. For this reason the price
myth must be addressed.
When people talk about price, they generally think in
terms of initial cost instead of life cycle cost. Price is only an issue
if you apply the 3,000 mile oil change rule to all motor oils alike.
In truth, the service life of synthetics can be extended much longer
due to their resistance to oxidation and other forms of degradation.
With proper filtration engine oil can be safely used for much longer
periods, and is thereby less costly than petroleum in the long run.
Add to this the reduced fuel consumption, fewer maintenance bills and
optimal performance characteristics and running anything but a premium
synthetic motor oil should not even be a consideration.
As you can readily see there is no single measure that
stands alone as the signature of superior performance. A motor oil serves
a variety of functions in a range of roles inside the engine. What tests
do show is that synthetic motor oils as a class are far and away superior
to petroleum based products.