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Re: synthetic oil in Tecumseh (no oil thread intended) ;)

To: dirtbeard <dirtbeard@pacbell.net>
Subject: Re: synthetic oil in Tecumseh (no oil thread intended) ;)
From: Trevor Boicey <tboicey@brit.ca>
Date: Wed, 09 Jul 2003 00:43:51 -0400
dirtbeard wrote:
> ... and 
> the manual from Tecumseh explicitly says "do not use muti-weight oils 
> due to increased engine wear and oil consumption."

   If it's in the Tecumseh manual, isn't that the final word on the topic?

   I don't work in the mechanical field and my mechanical knowledge is 
only average for this list, but I do work in an engineering field and 
have a little view on this one. (ok, I admit, it's a pet peeve, 
apologies if this becomes a rant)

   The fact is, the designers of the engine know the engine INSIDE OUT, 
they've seen hundreds, they know every failure mode, every wear point, 
every cost cutting measure, every design improvement that makes your 
version better than the one before, and everything that the next version 
has that yours doesn't.

   When you design a product, you know it to a level that frankly a lot 
of people don't comprehend, perhaps they just think it falls from space 
in one piece and collectively as humans we try to figure it out like voodoo.

   The designers know what makes the engine run best. This information 
goes into the manual. Maybe we'd be better off with a 90 page wear study 
on why multigrade is bad, but for whatever reason they don't explain, 
multigrade is not recommended, and they aren't just saying this to waste 
ink.

   When the designing engineers state their reasons, it's based on 
empirical fact, testing, design analysis, etc.

   Alternatively, when the "word of mouth" state their reasons, it's 
usually of the order of "I think that" or "I heard that" or "the guy up 
the street said".

   I point out this line:

> I know that side valve engines are characterized by comparatively higher 
> oil temperatures, and this probably the main reason for the mono-grade 
> specification.

   To me is the key word "probably".

   I guess it's your engine, but the people who designed your engine, 
the people who know it to a level that would shock most people, have 
made a statement for concrete reasons.

   ...why take the chance on overruling them based on a head scratch, a 
theory, and a "probably"?

   I'm sorry if it sounds like I'm picking on you, I'm not. I have no 
idea why they would recommend straight-weight either. However, doesn't 
it make sense to accept that they know for sure, we are only guessing 
and pondering things we only kind of understand, and to yield to their 
experience?

-- 
Trevor Boicey, P. Eng.
Ottawa, Canada, tboicey@brit.ca
ICQ #17432933 http://www.brit.ca/~tboicey/
After a while, you hardly even miss the respect.

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