[Vwdiesel] Oil stuff

[James Hansen]

Thought this might be of interest.

  Read this:
http://www.howstuffworks.com/question164.htm

and this.

http://auto.howstuffworks.com/framed.htm?parent=question164.htm&url=http://w
ww.vtr.org/maintain/oil-overview.html


Interesting stuff, might help with the oil discussion.

The biggest factor in starting a really cold engine is the pour point.  This
dictates how soon after startup you get oil pressure. Cold viscosity rating
is a factor, but different oils having the same viscosity rating can have
differing pour points.  The molecular structure changes more or less rapidly
for a given change in temperature.  For instance, the 0-40 synth I use in
winter, has a pour point of -48C which gets oil pressure up faster, and does
more for engine longevity in the long run.  Note, the Amsoil 20-50 has a
pour point of -38F, which isn't quite good enough for here, but impressive.
The Vaseline, uh, I mean Valvoline has the same 20-50 rating but a pour
point of -10.  You would be staring at a red oil light for a long time when
you first started your car around here. The redline has a pour point of -49
for a 20-50 oil.  WOW.  That would work here just fine.

Oil volatility is another factor that doesn't get much discussion, and has
more of  a bearing in diesels with EGR that those that don't.  The higher
volatility oils are murder in a non-modified TDI. You will get intake coking
with higher volatility oils due to the recirculated hot soot interacting
with the oil vapor in the intake air stream.  It is one reason to stick with
straight synth on your tdi- much lower volatility.  "straight synth" has
various meanings as well, I think we have gone over that enough in the past,
but I think straight synthetic is essntially a small handfull of oils like
Delo 100, Amsoil, Redline, Mobil 1.  The rest are legally called "synthetic"
as dictated by the courts, but not in the chemical sense. Can anyone add to
the list? It's good to keep track of this stuff, I tend to forget which ones
are "real" and which ones are "legal".
-James




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