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Date:         Wed, 2 Jun 2004 12:08:03 -0400
Reply-To:     Tom Miller <tmiller@VCMAILS.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Tom Miller <tmiller@VCMAILS.COM>
Subject:      Re: Viscosity degradation in oils
Comments: To: Al Knoll <al_knoll@PACBELL.NET>
Content-Type: text/plain; charset="iso-8859-1"

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 >


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