Return-Path: Received: from mv-relay-2.splasers.com ([65.119.109.149] verified) by logan.com (CommuniGate Pro SMTP 4.3c3) with ESMTP id 855308 for flyrotary@lancaironline.net; Tue, 05 Apr 2005 04:35:30 -0400 Received-SPF: none receiver=logan.com; client-ip=65.119.109.149; envelope-from=mike.wynn@spectra-physics.com Received: from usmtv-mx01.spectra-physics.com (firewall [172.22.1.10]) by mv-relay-2.splasers.com (8.11.6/8.11.6) with ESMTP id j357VjP24057 for ; Tue, 5 Apr 2005 00:31:45 -0700 Received: by usmtv-mx01.spectra-physics.com with Internet Mail Service (5.5.2653.19) id <2K1H8GMT>; Tue, 5 Apr 2005 01:34:26 -0700 Message-ID: <5FA49D34561C5945BA9258B31BF648800355DB62@usmtv-mx01.spectra-physics.com> From: "Wynn, Mike" To: flyrotary@lancaironline.net Subject: Break in oil Date: Tue, 5 Apr 2005 01:34:25 -0700 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2653.19) Content-Type: text/plain; charset="iso-8859-1" My impression is that the `no break-in' thing with synthetic oils comes from the lack of lighter fractions in the `pure' viscosity synthetic. There were a lot of oil leaks when fully synthetics were first introduced. It was discovered that the o rings and other `plastic/rubber' bits need some of the lighter oils in order to swell up and seat properly. The purely synthetic oils did not have these impurities hence the seals did not take up these lighter fractions and so the oil leaks. Take a new engine run on mineral oil and let the seals swell up and then change to a pure synthetic was the advice I heard (FWIW).... Mike