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From: smh@mhuxl.UUCP (henning)
Newsgroups: net.auto.tech
Subject: Re: What motor oil should I use?
Message-ID: <322@mhuxl.UUCP>
Date: Sun, 17-Nov-85 21:52:31 EST
Article-I.D.: mhuxl.322
Posted: Sun Nov 17 21:52:31 1985
Date-Received: Mon, 18-Nov-85 07:46:44 EST
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Organization: AT&T Bell Laboratories, Murray Hill
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From the keys of Steve Henning, AT&T Bell Labs, Reading, PA mhuxl!smh

> HISTORY OF MOTOR OIL 
> Quoted from RIDERANNUAL - 1984

Thanks for this excellent article on SA-SF and CA-CD etc.  BRAVO...

Question:
I have an air-cooled garden tractor engine that turns oil into "tar".
Previously I used Sears Spectrum 10W-30 and it would turn to a thick tar 
like substance which took an hour to drain a quart from the crankcase. Now
I use Quaker State 20W-50 motorcycle oil. The  motorcycle oil is stable.
Both oils are SD-SF:CC.  Why is the motorcycle oil much more temperature
stable or is temperature stability something not rated?