Making
Sense of Synthetic Lubricants
Don Stevens
Suncoast
Region - PCA
All of us have seen
countless ads telling us to change our engine oil every 3000 miles.
Some of us have watched the infomercials showing cars driving on the
racetrack with allegedly no oil or engines’ running on a stand
while the host pours sand and gravel over an exposed valve train.
Virtually all of the lube shops have some kind of magic additive
that they will say you need. What are we to believe? Or more
relevant, what is right for you? In becoming an Amsoil Synthetic
Lubricants dealer in 1998 I have done a great deal of research on
all kinds of lubricants and additives and in this article I will
share the facts about synthetic oils, petroleum based oils, and
additives so that you can make an informed decision about what is
right for your cars.
Oil
Classifications.
There are two
systems for oil classification. The SAE (Society of Automotive
Engineers) viscosity grade and the API (American Petroleum
Institute) classification that designates the type of engines for
which the oil was designed. The SAE viscosity grade is known as the
“W” number when classifying oils. Most oils on the shelf today
are multi-viscosity such as 10W30 or 20W50. In general, the lower
the first number, the better the oil will perform in extremely cold
conditions. Conversely, the higher the second number the better the
oil will protect at higher temperatures. If you were driving to
Minnesota in the winter you would want the lowest number you could
find like a 0W30. In our Florida climate however, a 10W40 or a 20W50
would be a better choice. The
API designation is typically an “S” designation for gasoline
engines and a “C” designation for diesel engines. Most of
today’s oils carry an SH,CF or SJ,CF designation signifying that
they are suitable for use in all gasoline or diesel automotive
applications. Those of you with diesel trucks or motor homes should
look for an API CG-4 rated oil.
Which brand you buy is largely a matter of preference.
Consumer Reports (6/97) found very few differences between major
brands of oil and all with the above SAE and API designations
performed fine in normal applications.
Synthetic
vs. Petroleum based oils.
Synthetic oils were
originally developed more than 50 years ago and became widely used
in jet engines. Less
than -120ºF ambient temperatures, 60000 shaft rpm, and 500º+F
exhaust temperatures proved too much for conventional oils.
Synthetics were created specifically to withstand these harsh
conditions and to date every jet engine in the world uses synthetic
lubricants. Amsoil introduced the first synthetic oil for automotive
use in 1972 and have continued to be at the leading edge of
development ever since. Mobil 1, undoubtedly the most recognized
name in synthetics, was introduced in 1976. Many companies have
jumped on the bandwagon and have since released synthetic lubricants
for automotive use and all are becoming increasingly popular for
their superior lubricating properties, superior ability to flow at
cold temperatures, and their ability to withstand high temperatures
for extended periods of time. Several new cars including the Porsche
996 and the Chevrolet Corvette LT-1 are delivered with synthetic oil
in the crankcase and require synthetic oil use throughout the life
of the car.
There are two
primary differences between synthetic oils and conventional
petroleum oils. These are the base stock or liquid that makes up the
volume of the oil, and the additive package. There are additives
(not to be confused with over the counter additives which will be
discussed later) in all oils that enhance the wear resistance
properties of the oil, enhance the ability of the oil to neutralize
acids and combustion by products, and provide corrosion protection
for the engine’s internal surfaces. The amount and quality of
these additives vary from one oil brand to another and this is a
very significant factor in the ability of an oil to adequately
protect your engine in all driving conditions. As a general rule of
thumb, the cheaper the oil, the fewer additives it has and
therefore, the less able it is to protect your engine.
There is one school
of thought that suggests that the only difference in synthetic oils
vs. petroleum oils is that the synthetics typically have a better
additive package. This statement is only partially true. Synthetics
almost always do have superior additives than petroleum oils. While
this does add to the cost of the oil, it also enables the oil to
last 3-5 times longer than conventional oil.
The synthetic base stock however, is of paramount importance
in the ability of a synthetic oil to flow at cold temperatures and
withstand greater amounts of heat over significantly longer periods
of time. Petroleum base stock molecules are long carbon chains that
are sensitive to stress and heat. Additionally, various paraffins
that are contained in all petroleum products regardless of how well
refined they are, cause oil to jell like a syrup at extremely cold
temperatures. At the other end of the temperature spectrum, high
engine temperatures and heavy loads (as typically found in towing or
racetrack applications) cause these chains to break down and the
base stock actually boils off causing a change of viscosity and the
formulation of sludge. This can happen at temperatures as low as 230º
F and by 250º F many petroleum oils are suffering significant
breakdown. Synthetic oils on the other hand are engineered
specifically to provide all the lubricating properties that natural
oil possesses, but none of the cold thickening or hot thinning
properties of petroleum oil. Synthetics are made up of uniformly
shaped molecules with shorter carbon chains which are much more
resistant to heat and stress. Synthetics can withstand temperatures
of 300ºF all day long and still protect your engine. In fact the
American Society of Testing Materials (ASTM) standard wear
resistance tests are conducted at 302º F. In this test synthetic
lubricants far out perform petroleum lubricants by factor of four to
one and greater.
Oil temperatures of
230ºF to 250ºF are not at all uncommon in driver’s education
track conditions, particularly in early 911s with no front coolers
or the marginally effective “trombone” oil coolers. These
temperatures are also fairly common in air-cooled engines in summer
time stop and go traffic with the A/C on. Further, temperatures on
the cylinder walls and in turbos are often over 450°F
for short periods of time. Liquid cooled cars can also have
extremely high oil temperatures even though the water temperature
may be normal. I observed this first hand several years ago in a
race car where the water temperature stayed right on 210ºF while
the oil temperature fluctuated between 240º F and as high as 280º
F depending on how hard the car was driven. Needless to say, this
particular car was running synthetic oil and remarkably ran about 50
hrs. between rebuilds with no significant wear.
The point of the
above paragraphs is quite simply that synthetic oils have a much
wider operating temperature range, by design, than petroleum oils.
Off The
Shelf Additives
There are countless
over the counter oil additives on the market, as there have been for
a number of years. In recent years a number of companies have
appeared on the scene with huge national television advertising
campaigns, racecar sponsorship, and more, all designed to make the
consumer believe that the products really work and you are doing
yourself a favor by adding these to your car. The fact is that these
products are not necessary, do very little to help your engine, and
in many cases may actually do more harm than good. The major car
companies do not endorse any of these products and in fact your
owner’s manual will undoubtedly advise you to avoid them.
Consumers Reports
did a test (10/98) in an attempt to verify, or rebuke, one
company’s ad which claimed that their product “bonded” to the
engines moving parts forming a protective barrier against wear. The
ad claimed that their test car ran all over Southern California, in
stop and go traffic, with the air on, for 4 hours and 40 minutes.
The ad also claimed that the only reason the driver stopped was to
get something to eat. Pretty unbelievable. In an attempt to prove or
disprove the viability of the ad, Consumer Reports tested two
Chevrolet Caprices, both with identical zero time rebuilt V6
engines. Both cars were broken in with normal petroleum oil per the
manufacturer’s recommendations. The oil and filter were then
changed with one of the cars receiving the prescribed dose of this
magic additive. Both cars were then driven for about 100 miles,
allegedly long enough for this magical bonding to occur, and the oil
subsequently drained. Both were then driven again, now with empty
crankcases, in normal traffic to see how long they would last.
Interestingly both engines failed, almost simultaneously, after
about 14 minutes of driving thus proving the claims of the additive
manufacturer to be nonsense. Consumer Reports notified the FTC of
the test and their results and the manufacturer was subsequently
forced to stop running the ad.
There are some over
the counter additives that contain Teflon or PTFE. Once again the
ads claim that the Teflon bonds to the internal working parts of the
engine forming a slippery surface (like your Teflon frying pan) and
therefore reducing wear. Fundamental laws of Physics prove that such
claims are impossible, as the temperatures in internal combustion
engines (200º-250ºF) are insufficient for any bonding to occur.
Further, independent oil analysis labs have observed that the
suspended Teflon particles actually tend to accumulate the
microscopic metals that are normal in engine oil formulating much
larger, and potentially much more harmful, deposits in engines than
would normally occur if straight motor oil had been used. In some
cases, the oil filters became clogged, oil pressures dropped across
the filter and oil analyses showed significantly more wear than oil
alone. Similar to the previous situation, the FTC challenged the
makers of products with PTFE on their claims of “coating of PTFE”
and “reduced engine wear” based again on Consumer Reports
findings of “no discernible benefits” from use of the product.
The makers of these products agreed with the FTC in a settlement to
stop using the above phrases in their ads.
Economics of
Synthetics vs. Petroleum Lubricants
All of the
manufacturers of synthetic oil tout the benefits of reduced wear,
more horsepower, lower operating temperatures, and improved fuel
mileage. All of these benefits are derivatives of better cold flow
characteristics and higher levels of friction reducing additives
that are found in synthetic oils. I can confirm better cold driving
characteristics, increased fuel mileage of nearly 10%, noticeably
lower operating temperatures, better heat dissipation capability,
and long term high temperature stability based on my own experience
with synthetic lubricants. Are these benefits enough, however, to
persuade average drivers to give up their trusted petroleum oils and
pay the extra price for synthetics? Enthusiasts, yes. Average
drivers, perhaps not. However, synthetic lubricants can endure extended
drain intervals, which is a major consideration toward
justification of the higher costs. This benefit is not widely
promoted by the major oil producers most likely because they want
you to pay a premium for their synthetic oils every 3000 miles just
like their regular oils. Most companies don’t bother to tell you
that synthetic oils are capable of going 25,000 miles or more
without significant breakdown. One customer told me he drove his
Toyota more than 50000 miles (with filter changes every 10000 miles)
before oil analysis results told him it was time for a change. It is
not uncommon for over the road truckers to go several hundred
thousand miles between synthetic oil changes. The short trips and
stop and go city driving that most of do is much tougher on motor
oil than over the road highway driving. In fact, frequent short
trips (2 miles or less) and stop and go some raters consider city
driving as extreme and our cars need increased protection.
Fortunately, we can achieve the superior protection and the economic
benefits of synthetic oils while staying within the recommendations
of our car manufacturers.
Consider the
following economic argument. If you change your oil every 3000 miles
at a quick lube center at an average price of $23.00 per change, you
spend $115.00 over 15000 miles. Most synthetic oil changes cost
about $50.00 (much less if you do it yourself) on which you can
drive 7500 miles very safely (a 7500 mile interval is within
virtually all manufacturers recommendations). Over the same 15000
miles, only two oil changes are required for an investment of
$100.00. A shop could charge up to $57.50 and it is still a
break-even proposition, plus you put a superior product in your car
and are receiving the additional benefits that synthetic lubricants
can provide. I typically drive about 12000 miles between changes
with a filter change and oil analysis at 6000. Even after 12000
miles oil analysis advises that the oil is “suitable for continued
use” and typically the wear metals are less than conventional oil
after 3000 miles. In fact in a test performed by Popular Mechanics
some years ago, oil analysis showed in New York City taxicabs that
there is typically less oil breakdown and less wear metals in Amsoil
10W40 synthetic oil after 60000 miles (albeit with filter changes
every 6000 miles) vs. conventional 10W40 oil after 3000 miles. As an
added benefit, less waste oil is being put back into the
environment. A true win-win proposition.
Conclusion
Most major brand
name petroleum oils perform adequately provided your driving
conditions are normal and provided you change the oil regularly
(remember, short city trips, driver’s ed track events, dusty
conditions, and towing are considered extreme). Over the counter
additives have been proven to be of little to no benefit, often do
more harm than good, and are a waste of money regardless of what you
drive and how you drive it. Finally, for those of you who drive your
vehicle hard, tow a trailer, drive very short distances, sit idling
and in stop & go traffic for long periods, live in a cold
climate and/or if your car runs hot, quality synthetic motor oil,
synthetic gear lube, and synthetic automatic transmission fluid is a
wise investment that will provide the additional protection you
require as well as last thousands of miles longer than conventional
lubricants.
Don Stevens is a mechanical engineering graduate of the Ohio State University and has been a member of the Suncoast Region of the PCA for 14 years. He is also a 10-year veteran road racer/driving instructor with hundreds of hours of seat time and several endurance races wins to his credit. For a free Catalog on the complete line of Amsoil products, please call or e-mail the author at 727-724-3431 or P911sc44@hotmail.com