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Re: synthetic oil consumption

> From quattro-owner@swiss.ans.net Thu Sep  8 18:02:51 1994
> From: Carl DeSousa <desousa@cisco.com>

> Lets not forget that synthetics work differently
> than fossil oils either.  Synthetics get in to places that fossil oils
> do not.  Maybe some engines weren't designed and toleranced to 
> use synthetics, *especially* after many miles of service and wear?
> Try running it on a 911,  ta dah... now all of a sudden oil leaks
> develop, and consumption increases.  

All Porsche 993's (the new 911) come filled with Mobil 1 and synthetic
oil is recommended.  I believe the oil change interval is 15K miles or
once a year.  As I recall, they did this so the car would do better in
the EPA mileage tests; it wouldn't invoke the Gas-guzzler tax.

I used Castol syntec during last winter because I do a lot of short
trips, and the engine feels "warmed-up" from the get-go with synthetic;
plus fuel economy is greatly increased.  Oil consumption was actually
less than with whatever the dealer puts in under the Audi Advantage.
The four V6s with which I have experience consume about a quart of this
conventional oil every 5000 miles.  The dealer has observed this
consumption rate--which is very low actually--and now over-fills by
about .5 quart--this way the cars don't go below the minimum mark by
the time they come back in 7,500 miles.

I think increased consumption of synthetics is really a matter of
perception:  if one changes one's mineral oil every 3K or so miles,
moderate consumption will go unnoticed, but extend the interval to 7K
or 15K and one will definitely have to add oil, even if consumption
drops.  This makes people think the engine is using more oil.

John Greenstreet, Senior Engineer           (jgreenst@motown.ge.com)
Martin Marietta Government Electronic Systems    Moorestown NJ 08057
WPI Class of '75, Temple Class of '94

My new car history:
1972     1975       1978      1982       1986        1989      1992
 VW  ->   VW    ->  Audi  ->  Audi  -> Mercedes -> Mercedes -> Audi
SBug   Scirocco   Fox GTI     4000S    190E 2.3    190E 2.6    100CS

POSSLQ's* new car history:
         1978       1981       1985      1988        1990      1993
       Triumph ->  Toyota ->  Toyota  ->  VW    ->   Audi   -> Audi
       Spitfire    Tercel     Corolla   Jetta GL      80       90S

*POSSLQ = Person of Opposite Sex Sharing Living Quarters
Note: All Audis and Mercedes above were sold to friends or family.