<VV> AR 15 Motor Oil

[Harry Yarnell]

This was an interesting article in the latest Riviera newsletter, thought I'd
share.

AT RANDOM
William C. "Bill" Anderson, P.E.


IT'S NOT YOUR FATHER'S MOTOR OIL!

Motor oil, like many of life's products, such as toilet paper or paper clips,
is an integral part of our daily lives. It is also so common that it is taken
for granted, reliably performing its function never once calling out for
attention. Those who collect cars, regardless of make or era, are acutely
aware of the revolution that has taken place in automobiles over the last 100
years. Equally revolutionary changes have occurred in the manufacture of
automotive engine oils. These changes are not just in the visible packaging,
but in significant changes in the composition and formulation of those oils.
Still, we cling to practices in using engine oil that are decades old.

In the last decade, there have been two major changes in engine oil
composition. Today's oils, those meeting the ILSAC (International Lubricant
Standardization and Approval Committee) GF-3 specification, are soon to be
replaced by new a specification, GF-4. The GF-4 oils will be first available
in July 2004 and GF-3 oils completely replaced by April 2005. These latest
engine oils are refined and blended with many additives to improve fuel
economy, control viscosity, and provide high temperature protection and
superior wear control. They also have significantly reduced quantities of
phosphorous, zinc, and sulfur once used to enhance wear protection but which
have proven to be harmful to air quality and the environment.

The net result of these improvements in engine oils enable them to perform for
longer periods of time and under more harsh conditions than their
predecessors. Yet, those in automotive maintenance -dealerships, independent
garages, and oil replacement specialists - continue to recommend oil changes
at 3,000 mile intervals when today's oil can be used much longer. On the other
hand, automotive engine manufacturers recommend less frequent changes -
DaimlerChrylser recommends 6,000 miles for Chrysler-badged cars and Ford and
Toyota each recommend 5,000 miles.

GM has taken a different approach that is instructive for all, whether you
drive a GM-engined car or not. Beginning in 1987, GM implemented its patented
Oil Life System (OLS) that is now installed in 95% of today's GM cars and
trucks. OLS is an indirect measure of engine oil quality. It is indirect
because it does not physically analyze the engine's oil, but infers its
quality by measurement of certain engine operating conditions and driving
factors. When an experienced-based algorithm incorporating these several
factors indicates it is time for an oil change, an orange light or dashboard
message is illuminated when the engine is started. The original algorithm was
based on 2 million miles of road and proving ground tests under four
conditions: easy freeway; high temperature and high load; extreme city where
the oil is warm;  and short trips with cold oil. After each test the oil was
tested and its extent of degradation determined. This test data formed the
basis for a computer model that employed engine operational data such as
temperature, revolutions, speed, etc. that enabled the car's computer to
calculate when the oil was nearing the end of its useful life. A factor of
safety was also built into this computer program.

After many years of experience with the OLS system, GM engineers have found
that engine oil changes, scheduled according to on-board monitoring, can last
up to 10,000 miles and even more with petroleum-based oils and still retain a
comfortable quality reserve to protect the engine. Synthetic engine oils
obtain even longer oil change intervals. The GM experience parallels the
findings of Mercedes-Benz which has a similar oil monitoring system.

The import of this information is that it is no longer necessary to change oil
based on an arbitrarily 3,000 mile limit. Rather, engine oil changes can be
scheduled based on use. The accompanying figure relates usage to mileage
between oil changes.  The one exception is that engine oil should be changed
at least once each year.

Summary

The bottom line is - Don't change engine oil unless you need to based on use!
For most collector cars that do not exceed the use limit, the best time to
change oil is in the fall when the car is "put to bed" for the winter. This
provides the engine with fresh oil in contact with all the engine's internals
and not oil that has been degraded and/or contaminated by use.

Admittedly, the dollar cost of frequent oil changes is small. However,
unnecessary oil changes are wasteful of a finite resource. With far better
engine oils today than years ago, it is sensible to take full advantage of the
improvements provided.
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