An end to the T**son thread - Beginning of another??

[quinn@hns.com]

To get everyone's mind off the now defunct (I hope) arachnid bites etc.,
I thought I might start up another old gem ... you guessed it ... OIL!

The following is Patrick Bedard's column from May's Car & Drivel/r.
But don't call me to respond ... I'll call you...

-Mark Quinn
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All about oil changes and buncombe stickers.
--------------------------------------------
By Patrick Bedard (Car & Driver, May 1998)

Every time a car comes back to my driveway from an oil change, I get
right after it with my Two-Point Anti-Infuriation Program.  First, a
flattened Maytag carton goes under the engine.  Leaks are infuriating.
Test cars get serviced at dealerships; from them, the likelihood of a leak
is 50-50.  The Cirrus came back with its drain plug finger tight; the
Blazer had no sealing washer under the plug.  Ten-minute oil changers are
better, I've found.

Second, I peel the "buncombe sticker" off the windshield.  You know that
see-through-plastic film with the blank for "Next Service," when a
mechanic ballpoints in an odometer reading 3000 miles down the road from
the one he saw?  Pure buncombe.  There's almost never good reason to
change oil in 3000 miles.

You may think we C&D guys are car experts.  Dealers think we're dupes,
same as every other customer.  Our long-tern-test Cadillac Catera went in
a bit early to Jim Bradley Pontiac-Cadillac-GMC Truck in Ann Arbor for its
first oil change, scheduled at 5000 miles.  The odometer showed 3993.
Naturally, it came back with a buncombe sticker advising next service in
3000 miles at 6993, or in three months.

Jim Bradley gets the Gold Gimme Award for this shameless grab for the
customer wallet.  For normal driving, the Catera owner's manual recommends
- and Cadillac confirmed by phone -  a 10,000-mile interval, or one year,
for all oil changes after the first one.  The exception is "short
trip/city" operation, and in that case, the schedule is 5000 miles or
three months.

Did the caring customer servers at Jim Bradley ask about our driving?
Nah, they just slapped on the usual buncombe sticker advising us to waste
70 percent of the 5.3 quarts they'd just poured into the crankcase.

The Catera's recommended oil change interval, like that of GM's other
European import, Saab, is exceptionally long.  Most automakers have been
recommending 7500 miles of normal driving between changes.  Ford is a
notable exception, calling for 5000 miles, or 3000 miles on the "severe-
duty schedule."

To find out more about oil life, I called Tim Eitzen, a staff engineer
at Chevron who specializes in motor oils.  He said the typical motor oil
is a complex cocktail, only about 80 percent of which is mineral oil
refined from crude.  Another 10 percent is a very heavy syrup known as
"viscosity index improver." It's there to keep the oil from thinning too
much at high temperatures.  The final 10 percent is a blend of various
chemical additives.

The mineral oil itself doesn't wear out.  Usually, driving depletes the
additives, and oil changes are scheduled in anticipation of when those
additives will be "used up."

Other factors, of course, can destroy the lubricating qualities of oil.
Back in the carburetor days, it was more common for excess fuel to work
its way past the rings and dilute the oil.  But generally speaking, motor-
oil life is determined by additive life.

Eitzen explains that the additives have three basic jobs.  Resisting
wear is the obvious one.  Anti-wear additives work by laying down a
sacrificial film on the wear surfaces.  Rubbing off the film consumes the
additive.

Neutralizing acids is another job for additives. Combustion produces
acids, which get into the oil.  Acids cause corrosion; they attack
bearings, removing microscopic amounts of metal.  It's another form of
wear, Eitzen says.

Then there's the matter of controlling deposits.  Insoluble compounds
are formed when combustion products react at varying temperatures in the
crankcase.  They start as tiny particles, and they like to adhere to other
similar particles, thickening the oil.  Some of them like to adhere to
engine parts, too.  Detergents, dispersants, and other agents are added to
surround these insolubles and keep them in suspension.  Changing oil while
these additives still have capacity drains the contaminates out with the
oil.  Once the additives are "full," deposits and sludge build quickly.

Eitzen, like the automakers, warns of driving extremes.  Short trips
wouldn't seem extreme, but they are.  Cold engines have richer fuel
mixtures and wider cylinder clearances, which result in more bad stuff
getting past the rings.  Cold engines don't cook moisture out of the
crankcase, either.  Idling in traffic also lets fuel past the rings.  The
more obvious extreme is the one few of us do-hard driving at high engine
temperatures, which oxidizes the oil and hastens wear.

Fine, but how short is a "short trip"?  How hard is "hard driving"?  The
Catera manual tries to narrow these ambiguities by saying to change oil on
the "short trip/city" schedule if any of the following are true: (1) Most
trips are less than 5 to 10 miles, particularly if outside temperatures
are below freezing. (2) Most trips include extensive idling in stop-and-go
traffic. (3) Most trips are through dusty areas. (4) You frequently tow a
trailer or use a car-top carrier. (5) The car is used for delivery,
police, or taxi service.

Owner manuals are clear about which viscosity oil you should use, and
sometimes they mention an API service code - the latest is SJ - but
they're agnostic about brands.  Not so with some car guys.  I happened on
an engine builder last summer who was a Kendall loyalist.  Eitzen
confirms, though, that all motor oils are blended, and their recipes are
tested, to specific performance standards.  Look for viscosity and for the
API letter code.  What's in the bottle may not be exactly the same from
one brand of 1OW-30 SJ to the next, but the different brands should
perform identically.

Then again, what's in the bottles of different brands may be exactly the
same.  There are only a few suppliers of additives.  Not every brand has
its own base oil plant.  Moreover, shipping oil around the country raises
prices.  So regional blenders put the same recipe in bottles wearing
different brand labels.  Major brand oils are sold in store-brand bottles,
too.  The catch, Eitzen says, is that some store brands are done by
independent blenders with questionable quality control.  Which is which?
No way to know.  Safeway is good with pancake syrup, but what does that
say about motor oil?

For his own cars, Eitzen is inclined toward 3000-mile oil changes.  "We
always say oil is too cheap," he laughs.  "Why take a chance?"

But as a guy who engineers motor oil for a living, what does he
recommend for the rest of us?  "Change when the car manufacturer says to."

As I said, those stickers are pure buncombe.