Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84 exptools; site whuxl.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!whuxl!unpfc1 From: unpfc1@whuxl.UUCP (CALL) Newsgroups: net.auto.tech Subject: Re: Re: What motor oil should I use? Message-ID: <822@whuxl.UUCP> Date: Fri, 15-Nov-85 10:12:38 EST Article-I.D.: whuxl.822 Posted: Fri Nov 15 10:12:38 1985 Date-Received: Sat, 16-Nov-85 09:07:22 EST References: <561@ihwpt.UUCP> <2435@cal-dbb.fluke.UUCP> Distribution: na Organization: AT&T Bell Laboratories, Whippany Lines: 99 > Hello! > > I have used only 20W-50 oil for the past ten years or so. According to my > Toyota owner's manuals, this is good protection down to 10F. And it sure > makes me *feel* more comfortable on really hot days in the summer. > > If the tradeoff is thick oil & better protection versus thin oil & better > gas mileage, I would choose the better protection. > > So what does everyone think? Nowadays, 15W-50 is available. Would that be > perfect? HISTORY OF MOTOR OIL Quoted from RIDERANNUAL - 1984 "Back in the 1930's, Society of Automotive Engineers (SAE) developed service classifications for engine oils. The first were SA and SB. SA is for utility motors such as generators operating under low stress conditions. This classification has no performance requirements. An SA oil may have no additives at all, or it may contain pour and foam depressants, to preventthe oil from frothing inside the engine. SB is now described as a minimum duty oil for engines operating under such mild conditions that very little protection is required. SB oils provide only anti-scuff capability and resistance to oxidation and bearing corrosion. This is the kind of oil you might pour in your lawnmower today, but could never imagine putting in your car, let alone a motorcycle. Yet for three decades this type of oil was "the" standard motor oil. It was not until 1964 that SAE developed a superior oil classification :SC. Oils with this designation contain additives that help control high and low temperature deposits, wear, rust and corrosion. Oils meeting the SC standards were a significant step towards increasing the life of engines and meeting the needs of the powerful passenger car motors that were being produced during the heyday of the muscle cars. But they were not good enough. Just four years later, even tougher classification had to be developed: SD. These oils provided yet stronger protection against high and low temperature engine deposits, wear, rust and corrosion. The new classification should have been enough to last another 30 years. But Detroit makers began requiring stiffer oil abilities by 1971. Small cars were coming out of the factory doors in large numbers - Ford's Pinto and Chevy's Vega showed up around then. In addition more and more foreign cars with higher revving, small engines were appearing on our shores. These machines demanded a lot from an oil. So in 1972, the SAE came up with what they figured had to be the oil category to end all oil categories - SE. It provided yet more protection against oxidation high-temperature engine deposits, rust and corrosion. SE was the top oil classification during the 70's, but in 1980,it was replaced by the latest classification - SF. This oil provides even more protection - particularly against oxidation and wear. The "S" in these classifications stand for spark ignition - ie. gasoline engines. Classifications that start with "C" specify oils for diesel engines(C for compression ignition)." OIL VISCOSITY The numbers after the service classification refer to the viscosity of the oil which is a measure of its resistance to flow at certain temperatures. The numbers also give you an idea how thin the oil gets when it gets hot and how thick a layer of protecting slipperyness will stay between the moving metal parts in the engine. The "W" rating, accompanied by a lower number placed before it, is a measure of the flow rate at 0 degrees F. However this rating tells you more than just winter-time performance. It - more importantly - is a measure of its "startability" or how quickly it will flow to needed areas when the engine first cranks over. A low number before the "W" is not a bad idea anytime you care about limiting engine wear. GM OIL RECOMMENDATIONS I own a 1984 Chevy Celebrity with a 2.5L 4 cylinder engine. The recommendations for oil suggest 5W-30, SF classifications with 10W-30 as a second choice. I take these recommedations seriously and have found that Valvoline produces a 5W - 30 oil that can sometimes be purchased on sale. 10W-40 weight oil is specifically *NOT RECOMMENDED* according to the owners manual and to several mechanics I have querried on the subject. They seem to feel that the ability to quickly flow and protect camshaft bearings during startup is the reason for the recommendation. Hope this helps . Pete Call > > -- > --bruce > -- > > ________________________________________________________________________ > Bruce M. Reynolds {decvax,ihnp4}!uw-beaver!--\ > John Fluke Mfg. Co., Inc. {sun,allegra}!---> fluke!bruce > (206) 356-5421 {ucbvax,hplabs}!lbl-csam!--/ *** REPLACE THIS LINE WITH YOUR MESSAGE ***