<VV> AR 15 Motor Oil / Old car engine realities

[Louis C. Armer, Jr.]

Hey Harry and all, These updates on oil technology are always informative
and useful to apply to new car engines and conventional old car engines.
However, even when applying the new standards and claims to a standard
old car engine I hesitate to take all the "pat" answers as gospel. We all know
how metallurgy and computer measurements of new car engines specs have
allowed much much smaller clearance tolerances in engine and carburetion/
fuel induction and so all  the new oils are developed and sold with this in 
mind.
They don't take into account how much more blowby old engine tolerances
produced, how much metallurgy science has decreased the need for larger
clearance tolerances, and the huge heat range our Corvair engines normally
operate within. Our carburetion is a constant pollutant of crankcase oil 
and the
extreme heat range of our Corvair engines accelerates viscosity breakdown. I
think I will stick with Dino oil and still change oil and filter every 
3-4000 miles.
My experience tells me that it works quite well with our mature cars.

Chuck Armer
////////////////////////////////////////////////////////////////////////////////
>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.
>
>big snip

>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.
////////////////////////////////////////////////////////////////////////////////////////////////// 


Corvair Atlanta, BOD
CORSA MEMBER
CORSA Tri-Membership Chairman
http://carmerjr.home.mindspring.com/