> 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.
Do you think they also knew what improvements would be made to commonly
available lubricants in the next 30 or 40 years ? For example, 30 years ago
viscosity improvers had a definite tendency towards early breakdown, leaving
the oil thinner than even it's "winter" weight. Today's motor oils seem to
have improved a great deal. From personal observation, the same engine that
used to tear up the VI in multiweight oils in only a few thousand miles,
will go 10,000 without doing so today.
There's also the problem that the designers goals are not necessarily the
same as mine. Cost, for example is a primary concern when designing a
product; while long life isn't necessarily. Most manufacturers lose
interest once a product always lasts beyond it's warranty period, and if it
typically lasts 3 or 4 times that long, it's probably over-designed and
costs too much.
Car makers in particular are sensitive to even $.001/car and so would not
use a more expensive oil, even if it made the difference between the engine
lasting 100,000 miles and 200,000 miles (assuming of course the warranty was
substantially less than 100,000). And of course, it looks bad to recommend
a better oil than they use, so that's not going to happen either.
Last, Sturgeon's Law applies to engineering too ... <g>
Randall - also a professional engineer (software)
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