Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site umcp-cs.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxj!ihnp4!zehntel!hplabs!hao!seismo!umcp-cs!prophet From: prophet@umcp-cs.UUCP (Dennis Gibbs) Newsgroups: net.auto Subject: Multi-Viscosity Oils Message-ID: <131@umcp-cs.UUCP> Date: Wed, 26-Sep-84 17:42:54 EDT Article-I.D.: umcp-cs.131 Posted: Wed Sep 26 17:42:54 1984 Date-Received: Fri, 28-Sep-84 06:47:47 EDT Distribution: net Organization: U of Maryland, Computer Science Dept., College Park, MD Lines: 33 <> Several people have recently expressed interest in exactly what is a multi- viscosity oil. The answer is actually quite simple. A multi-viscosity oil, such as a 10W-30 oil, means that at zero degrees fahrenheit, the oil will have the same thickness as a straight weight 10W. It also means that at a high temperature (I think the standard is 210 degrees) the oil will have the same viscosity as a straight 30 weight. This does NOT mean that the oil doesn't get thicker as it gets colder, it just means that its viscosity value changes from a 30 weight at operating temperature to a 10W weight at zero degrees fahrenheit. So, in essence, what is happening is that you are getting the high-temp- erature protection of a 30 weight, and the low temperature protection of a 10W weight. Both a straight 10W weight and a straight 30 weight get thicker when it gets cold, but a 10W weight is always thinner than a 30 weight. Also, there is a common misconception that the heavier the oil, the better the oil protects. This isn't necessarily true. What is important is how much temperature and pressure the lubricant can take without oxidizing ex- cessively. This is where Synthetic lubricants excel. Dennis -- Call-Me: Dennis Gibbs, Univ. of Md. Comp. Sci. Center. UUCP: {seismo,allegra,brl-bmd}!umcp-cs!prophet CSNet: prophet@umcp-cs BITNET: GIBBS@UMDB ARPA: prophet@Maryland