Well stated.
----- Original Message -----
From: "Al Knoll" <al_knoll@PACBELL.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, June 02, 2004 11:28 AM
Subject: Viscosity degradation in oils

> The kodachrome fades quickly now but I recall a good summary of multigrade
> oils to mention that the viscosity of the oil is dependent upon the length
> of the polymer chains.   Adding "spring-like" polymers to a base oil
> provides the multi-grade effect.  Most "big-rig" diesel herders use a
single
> grade oil often just plain old 40W for most service.  "DELO" was a moniker
> that came to mind for this service.
>
> The oil is primarily valuable as a lubricant and as a heat transport
> mechanism a secondary effect is as a suspending medium for particulates.
> Its viscosity degrades when the polymers get shorter.  This is generally
> caused by breaking the polymer mechanically.  Divine guidance, facing
mecca,
> or use of qualified exorcists will not reduce this degradation.  The
> polymers must be meticulously re-joined using your choice of adhesives
such
> as gorilla snot or Barge's cement OR simply replaced by new longchain
> polymers in the form of new oil.
>
> The filter is a dirt catcher.  The more dirt it catches the less dirt or
> particulates remains in the oil.  It has VDL to do with the viscosity of
the
> oil, it has a lot to do with the abrasive qualities of the oil/particulate
> mix.  Whether or not one uses Dino or Sintho oil matters little to the
> accumulated particles.  Those particles produced as combustion by products
> will be there slowly wearing away at the bearing surfaces until removed
from
> the oil.  The filter helps, changing the oil helps but in the end entropy
> wins and the motor wears out.  Just as perfect health is the slowest
> possible rate at which one can die, engine health is the acceptable rate
at
> which a motor can wear out.
>
> So if the filter was perfect and no particles were present, ever, then the
> problem would reduce to  polymer destruction and subsequent reduction in
> viscosity.  As long as there is an acceptable film of oil on plain
bearings
> wear is almost non-existent.  Scuffing occurs when the film is broken
either
> by pressure or by ... particles.  The film degrades as the polymers are
> broken.  QED.
>
> At the film lubricated piston ring/cylinder wall the abrasive content of
the
> air has FAR more effect on wear than the gradual polymer degradation.
>
> SAE has bags and bags of data in the literature on these phenomena.
>
> The vanagon motor is pretty dumb.  It has no knowledge of what kind of
> vehicle it is in.  RVC
>