Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site ucla-cs.ARPA Path: utzoo!watmath!clyde!burl!ulysses!mhuxj!houxm!ihnp4!zehntel!hplabs!sdcrdcf!trwrb!cepu!ucla-cs!duane From: duane@ucla-cs.UUCP Newsgroups: net.auto Subject: oil viscosity Message-ID: <1326@ucla-cs.ARPA> Date: Sun, 23-Sep-84 17:07:56 EDT Article-I.D.: ucla-cs.1326 Posted: Sun Sep 23 17:07:56 1984 Date-Received: Wed, 26-Sep-84 06:06:29 EDT Organization: UCLA CS Dept. Lines: 21 I was suprised by a recent statement made asserting that a multi-viscosity oil got MORE viscous when cold. I assume that was a typo or perhaps someone can correct me. If I remember my fluid dynamics (doubtful), viscosity is a measure of a fluid's resistance to motion through it. The viscosity of air is much lower than water, just try running through them both. One would hope that cold weather would find the oil "thin" so that starts would be easier. I remember an article from years ago that was neither for nor against multi-viscosity oil but was against misleading advertising claims. Yes, there were additives to prevent "molecular bond breakdown". Yes, multi-viscosity oils change viscosity over a wide range of temps. No, viscosity is not a measure of an oils ability to lubricate. The article claimed that, in theory, temperatures could increase, viscosity would increase, but at some point the oil's ability to lubricate might decrease. Within reasonable temp ranges this might not happen. Bottom line - just because your oil is getting "thicker" doesn't mean it is still lubricating. Since I'm not a ChemEng or otherwise qualified, I'll stop here and ask a more qualified respondent to verify or refute my memory.