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From: rct@occrsh.UUCP
Newsgroups: net.auto.tech
Subject: Re: Syn Oil and Breakin
Message-ID: <1300001@occrsh.UUCP>
Date: Fri, 6-Dec-85 15:04:00 EST
Article-I.D.: occrsh.1300001
Posted: Fri Dec  6 15:04:00 1985
Date-Received: Tue, 10-Dec-85 06:34:02 EST
References: <746@drutx.UUCP>
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Nf-From: occrsh.UUCP!rct    Dec  6 14:04:00 1985


/* Written  1:57 pm  Dec  2, 1985 by pagiven@drutx.UUCP in occrsh.UUCP:net.auto.tech */
/* ---------- "Syn Oil and Breakin" ---------- */

I have heard from more than one source now, that before using  syn-
thetic  oil,  the  engine  should have 6K to 8K miles so the engine
could properly "break in," "seat," or "become seasoned."

What exactly do these terms mean, anyway?  Is it necessary  for  an
engine  to wear out to a certain degree before the process is stop-
ped with a changeover to synthetic oil?

...

/* End of text from occrsh.UUCP:net.auto.tech */

The mating surfaces of the piston rings and the cylinder walls in a
brand-new (or freshly overhauled) engine are such that the piston
rings do not seal the combustion chamber as well as they will after
a "break-in" period of several miles (depending on driving style,
piston ring material, etc.).  During this "break-in" period, the
friction between the rings and the cylinder walls serves to smooth
out to some degree most of the surface irregularities, resulting in
slightly higher compression and lower oil comsumption than when the
engine was first put in service.  This is why most automobile owner's
manuals will caution that some oil consumption during the break-in
period is to be considered normal.

The debate rages on as to what constitutes a proper break-in period
for new cars.  The facts as I understand them imply that most new
car engines are past the critical portion of the break-in period (the
first few hours of run time) by the time the new car is delivered to
the customer.  This would explain the low (practically non-existent)
oil consumption experienced by most owners of today's new cars during
the first 5,000 miles.

To answer your question about using synthetic oils in new cars:
Running the oil that came with the car until the first oil change
is generally a good idea.  When to change the oil?  I disagree with
the 7,500-mile oil change intervals recommended in many owners manuals
and regard them as too long to properly preserve an engine past 100,000
miles.  I've had good luck with a 5,000-mile interval, but this depends
on many factors relating to driving style and environmental conditions
such as climate, dust, etc.  I recall reading an article about a cab
driver back east that had over 1,000,000 miles (NOT a typo) on a `50's
vintage Cadillac (original engine, never overhauled)!  He changed the
oil every 100 miles though...

--Bob Tracy
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