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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