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Path: utzoo!watmath!clyde!cbosgd!ihnp4!ihuxm!pnovak
From: pnovak@ihuxm.UUCP (paul novak)
Newsgroups: net.auto
Subject: Oil Viscosity (long)
Message-ID: <1174@ihuxm.UUCP>
Date: Tue, 11-Dec-84 16:11:48 EST
Article-I.D.: ihuxm.1174
Posted: Tue Dec 11 16:11:48 1984
Date-Received: Wed, 12-Dec-84 05:33:42 EST
Organization: AT&T Bell Labs, Naperville, IL
Lines: 43

a few weeks ago i posted a question to this newsgroup regarding oil 
viscosity: specifically why in a cold winter climate, you don't always 
want the lowest "W" rating.  (question arose because the owner's 
manual for my parents' 84 pontiac parisienne (8 cylinders) recommends 
10W-30, but recommends 5W-30 for my sister's 84 sunbird (4 cylinders)).  
i never received any replies from that question and went off trying to
gather some information myself.  i learned a little, thought i'd report it.

i first called GM.  was told 5W wasn't needed in the large engine cause 
it's starting system could start the car with a 10W oil, but could not 
answer why the 5W wasn't preferred since it should make starting easier 
in any car.  then i called shell and mobil, who pretty much said i 
should use what the owner's manual said.  finally i called the american 
petroleum industry in washington and gathered the most, but still 
incomplete, information.

from API (this is all one person's opinion/knowledge) i learned that 
my premise is valid.   the auto manufacturers are allegedly pushing 
for 5W-30 oil in all 1986 model cars.  they have to get support of 
the oil industry and the EPA.  to do this, they have to prove that 
5W-30 oil is better for the engine than 10W-30.  i asked the API 
person why it always wouldn't be better, and all he could say was 
that there were different additives in 10W-30 than 5W-30 oil.  
apparently, the EPA is involved to insure that if 5W-30 oil is 
used there will be sufficient engine protection in the long run
to minimize pollutants.  also, the oil/lubrication don't appear 
eager to accept the auto manufacturers test results.  this may 
be because the oil companies think the auto manufacturers are up 
to something to intentionally shorten the life of a car (gee, imagine
that) and that blame would eventually fall on the lubrication industry,
or because  5W-30 oil is manufactured only by a few oil companies 
and they may be foot-dragging until all of the oil companies are 
ready to produce it.

the personal recommendation to the person i spoke to was to use only
the recommended oil weight during the warranty period, but that
5W-30 oil (or 5W-40 if your manual calls for 10W-40) would be
better for your car.

that's all.

paul novak
ihuxm!pnovak