I have been in the auto repair industry since 1972 ... hummmm, a simple
calculation of the math illustrates that I have been in car repair for, uh,
well, let's not go there. It makes me depressed. You do the math and keep it
to yourself. At any rate, enough about my mid life crisis. Let's talk about
oil change intervals.
For years the accepted oil change interval (as per the carmakers) has been
every 3 months or 3 thousand miles, whichever comes first. Why? Because the
oils of yesterday degraded and broke down when left in the crankcase
environment for longer than the prescribed interval. The combination of
heat, friction, and the oil oxidizing over time resulted in an unholy
clothing of the engine's internal parts called sludge. As an automotive
machinist for a good part of my career, I can tell you that sludge is an
engine killer. Sludge takes a greasy, cake-like oily form and plugs oil
return passages and acts like a sponge and soaks up good oil to grow its
grotesque form starving the engine of vital lubricants. Once established,
engine heat crystallizes it to a hardened rock of ughhhhhh, I have spent
many an hour scraping and yes, sometimes chiseling established sludge from
the inside of an engine before performing a machining operation on it! As
the machinist prepares to perform a machine operation on a cylinder head,
crankshaft, engine block or the likes he/she must clean their work
meticulously before performing the prescribed operation. If the sludge is
not cleaned properly, the result will be a failed engine.
Why this lesson about sludge? Because without clean good quality oil in your
car's engine, it will develop sludge and cause premature engine failure.
Now more than ever before, vehicle engines operate at high heat and close
tolerances. The reason for this is the Federal Emissions mandates the
government has imposed on the carmakers. Vehicles have to emit a smidgeon of
the tailpipe emissions they did a decade ago. Carmakers have risen to this
occasion by increasing combustion chamber temps with higher compression
engines, running leaner fuel systems, adjusting ignition timing for optimum
emissions, narrowing cooling system water jackets, and tightening engine oil
tolerances. All this makes for hotter running engines that emit less
tailpipe emissions. Putting these demands on engines requires a lubricant
that can stand up to this harsh environment. Hence, petroleum companies'
work hand in hand with carmakers to develop engine lubricants to meet the
requirements and demands of a particular powerplant, still delivering the
advertised horsepower and torque output that consumers expect. Research and
development between carmakers and petroleum companies has resulted in
improved engine lubricants that properly lubricate your vehicle's engine as
well as keep the inside clean of sludge buildup, AND CAN GO LONGER BETWEEN
OIL CHANGES!
A pioneer in extending oil change intervals ...
A few years back, GM introduced a system called the OLM (Oil Life Monitor)
system. This system had been in testing since 1984 and actually was put into
some Buicks on a test basis. The goal of this system? To extend oil change
intervals and attain bragging rights to having a more maintenance-free
vehicle. The OLM monitors crankcase temp, moisture, and combustion chamber
events (this represents the actual work the engine is doing while in
operation). By closely monitoring these elements of engine operation the
system can measure the serviceable life of the oil to within 10%. After
officially introducing the OLM with virtually no engine failures attributed
it the OLM, GM changes their service recommendations to what they called an
"Enhanced Maintenance Schedule." With the Enhanced Schedule, the motorist
need only follow the dictates of the OLM and have other scheduled services
done at prescribed intervals.
Ford Motor Company has followed GM into the extended oil change interval
march. Four months ago (March of this year) Ford announced that they are
revising engine oil change intervals to every 7500 miles. The reason?
Quoting the article from the Associated Press dated March 22nd, 2007:
"Not only are modern oils better, modern engines are also better. You
don't have carburetors metering poorly on winter mornings, tolerances are a
lot tighter, and operating temperatures are typically a little hotter,
helping to cook off the junk that accumulates in the oil. Ford contends that
its customers prefer a set amount of miles between changes. The automaker
also cites the environmental benefits that come from less waste oil,
monetary savings, as well as extensive tests as positive aspects of the new
recommendation."
Yes oil is much better than it used to be, engines are better protected with
today's new lubricants but the same old logic still applies to the oil
filter: always use a good quality filter when having the engine oil changed.
The filter is the storehouse for dirt in the engine and when it doesn't do
its job, the engine suffers internally. When dirt and grit are allowed to
circulate over, within and on the engine bearing surfaces, cylinder walls,
crankshafts, piston rings, camshafts and virtually all metal mating
surfaces, they are damaged resulting in wider oil tolerances, lowered oil
pressure and untimately prematuire engine failure.
While I concur with R&D results over the years with respect to oil change
intervals, I am still squeamish about leaving petroleum-based oil in an
engine for 7500 miles. I guess I just know too much based on personal
experience.
So while yes, I have revised my thinking regarding extending oil change
intervals:
Here are my revised oil change recommendations: change regular petroleum
based oils every 4-5 thousand miles and synthetic every 5-7 thousand miles.
There, those of you that for years have criticized me as being in the back
pocket of petroleum companies for recommending 3 thousand mile oil changes,
are you happy now?
'Til next time ... Keep Rollin'