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From: pwv@fluke.UUCP (Pat Vilbrandt)
Newsgroups: net.auto.tech
Subject: Re: MOBIL 1 info. request
Message-ID: <1030@vax2.fluke.UUCP>
Date: Wed, 27-Nov-85 11:57:19 EST
Article-I.D.: vax2.1030
Posted: Wed Nov 27 11:57:19 1985
Date-Received: Thu, 28-Nov-85 19:09:58 EST
References: <711@drutx.UUCP>
Distribution: na
Organization: John Fluke Mfg. Co., Inc., Everett, WA
Lines: 65

> Having paid an arm and a leg for an oil change using MOBIL 1
> ...  MOBIL states that the oil is good for
> 24,000 miles or one year (whichever comes first).
>  
> What do YOU think?
>  
> drutx!grl		Randy Lyman

I believe Mobil.  Let me digress a minute however on a recent experience with
organic motor oil:

A friend called me the other day saying the engine in his '82 Subaru was making
horrible banging sounds, so he towed it to my house, and sure 'nuff, it sounded
horrible.  What's the problem?  Quick compression check; one cylinder slightly 
low, but acceptable overall.  So, we undid 80,000 hoses and tubes and pulled
the engine out.  (It was obvious by now from turning the main engine pulley 
by hand that the connecting rod bearings were shot -> lots of play.)

As we here tearing the heads down, we found that they were full of gunk - 
looked like asphalt (which is, after all, one of the "bottoms" left over from
refining lubricating oil from crude).  Hmmm, I thought.  So I asked my 
friend, "How often have you changed the oil in this puppy?"  He slowly cleared
his throat and said quietly "'bout four or five times."  The car had 103k 
miles on it!  Enough of this "asphalt" had found its way into the oil pan to 
plug the oil intake screen.  No oil pressure -> trashed bearings.  Today, after
machining the crank, re-conditioning the conn. rods and new bearings (and
scraping lots of gunk!), my friend's Subaru is back on the road.

The moral of this (true) story is that ORGANIC motor oils have to be changed
often because they BREAK DOWN.  This break down is largely caused by heat,
not from combustion by-products, dirt, dust, water, whatever.  Most of the 
additives (detergents) put in organic motor oil are there to combat this 
problem, ie. to protect the engine from the oil!  True, the above is a bit
extreme, but I question the recent practice of many auto manufacturers 
extending oil change intervals to 10,000 miles.  Organic oils just haven't 
improved that much.

Don't believe me?  Well, let me offer this other true story:

I started running Mobil 1 in my '77 Subaru 4WD wagon after the first 6000 mi.
oil change, and changed it thereafter every 15-20K miles.  At about 90k miles, 
the water pump seal failed, the engine lost coolant and the *cylinders* warped.
In the process of tearing the engine down to have the cylinders re-bored, I
found almost no bearing, ring or cylinder wear and the engine was the cleanest
I had ever seen - no sludge build up in the heads and almost no varnish!  I got
the impression that the engine would have gone forever if it hadn't overheated.

Note that I had driven the car in temperatures over 100 degrees in the summer 
and below zero in the winter.  Also, back then, Mobil 1 was 5W-20, not 5W-30
as it is now (which I believe is better).

Well, this is getting too long, so, in summary, if you're using Mobil 1, you'll
be okay if you change it every 24,000 mi.  If you're using organic motor oil,
change it as often as you can afford, every 5,000 is probably okay, more often
is better.

-- 

   Pat Vilbrandt
   John Fluke Mfg. Co., Inc.
   Everett, Washington USA
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