From: vbreault@rinhp750.gmr.com (Val Breault)
Newsgroups: rec.autos.tech
Subject: Re: Pre-luber summary & Oil Changes
Date: 31 Aug 92 13:39:46 GMT
Organization: General Motors Research Labs
In-reply-to: paulw@hpspdla.spd.HP.COM's message of 28 Aug 92 16:19:23 GMT

In article <15200042@hpspdla.spd.HP.COM> paulw@hpspdla.spd.HP.COM (Paul Welch) writes:

   Thanks for all of the responses to my question about pre-oilers. 

For my part, you're welcome.  

<much good stuff deleted>

   Finally, I'd like to plant another seed for some more discussion.
   Being an engineer, I've been taught that you make guesses based on
   theory, and make decisions based on DATA.  Where is the data for 
   the suggested frequency of oil changes???  I'd especially like to hear
   from our friend at the GM research center on this one.  

Hmmm....  I guess he means me. 

I do not have that information handy Paul, but I will tell you via
private Email where to write for it.  

I'm pretty sure that you'll get an answer like "it depends".  It depends
on the average and peak temperature of the oil.  It depends on the 
kind of driving.  It depends on the weather...... it depends.

Since most folks don't have access to a chemistry laboratory but every
car has an odometer, the folks that build and warrant the engines came
up with the mileage method.  It's not exact.  It may not even be close.
But it does provide a safe margin for error and it is easy to figure out.
  
                                                       Or from someone
   at a petroleum company.  A very close friend's father used to work at
   a petroleum product analysis firm, where, among other things, they 
   analyzed oil from various motors and equipment.  He was also a pilot,
   and a certified airframe and engine mechanic.  He preached the 
   following:  Oil doesn't really ever need to be changed.  I know that
   this is a RADICAL concept for most of us.  He said that with todays
   quality lubricants, the only real loss that all the analyses showed
   was that the ADDITIVES tended to dissipate or fail in the oil.  
   Just adding new oil when the motor needed it, and CHANGING the filter
   regularly, was all that was really required.  I'm sure the folks at
   Pennzoil wouldn't agree!!!  Of course the $64 question is: would I
   try this?  Don't know yet, not enough data !!

Your friends father is (mostly) right.  This presumes that the engine
leaks or burns oil at a sufficiently high rate that replacement oil 
is put back into the engine at an adequate rate.   (Where did I learn
to write like that???)  Let's try that again....  If you have a very 
tight engine doesn't leak oil and doesn't burn oil then the rate of 
replacement will be quite low.  The old oil with the exhausted 
additives will lubricate the engine quite well, but the anti-corrosive
additives will be depleted and the acidity of the oil will rise.
I suppose that if you had access to a chemistry lab you could monitor
the condition of the oil and determine precisely when your oil needed 
changing.  Alternatively you could follow the old rules of thumb and 
change it before it was absolutely necessary.  

As long as anyone is under there changing the filter they should spend 
the extra 6 minutes and 6 dollars to assure that the job is done as 
close to "right" as they can get.  It's the CHEAPEST way to engine 
longevity that I'm aware of.  Every single engine that I've seen with 
exceptionally high mileage has had a regular oil change schedule for 
most or all of its life.  There's no gimmic, there's no potion, there's 
no substitute for good lubrication.  That doesn't end at lubricating 
the engine.  The suspension, the door hinges, the linkages, the 
transmission....   If it *CAN* be lubricated, it *SHOULD* be lubricated.  
Become a lubricant fanatic and you'll become the proud owner of very 
long lived and well running "things".  

(Every summer when I cart out the electric fans I disassemble them, 
clean them and lubricate them.  I'm still using the fan my grandmother
used.  It was old when I was born and I'm now well into my fourth 
decade...   As a younger man I worked in a machine shop that was
populated with ANCIENT but well running machines that were converted
from central power....  The boss was a lubricant fanatic too.)

I know that you agree Paul, I just wanted to say it once again while 
I had the soap box.  I'll climb down now and let the next person
have it for a while.  

-val-
--

Val Breault - vbreault@gmr.com - N8OEF
General Motors Research and Environmental Staff.
The opinions expressed by the author do not necessarily reflect 
those of the GMRES or the General Motors Corporation.