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From: The Marchands (no email)
Date: Sat Nov 02 2002 - 11:36:07 EST
Karl:
I ran diesel construction machinery for a number of years (Detroit Diesel
GM671s)- some in New England in the winter. FWIW, we learned to start our
diesels in -20 degree weather by blasting a kerosine heater on the oil pan
and block for a half hour or so before starting. This was portable machinery
and plug in block heaters just weren't practical.
Yes, some diesel manufacturers are inflexible in so far as multigrade oil. I
think that the reason is that a diesel often runs at a relatively high
percentage of its rated output (unlike a car) and so once it reaches
operating temperature, it really doesn't matter what the ourtside air
temperature is- the oil temperature, bearing temperatures, etc are as high
as if it were summer. So diesel engines need good lubricity and the
multigrades- particularly the ones of a decade or so ago (which were
essentially rubber disolved in oil), have considerably less lubricity.
The synthetic oils today are pretty close to the natural lube oils in
lubricity, and the multigrades have also gotten better. So some engine
manufacturers- Yanmar for one, will allow synthetics or multigrades. OTOH
Yanmar will not relax the oil change interval for synthetics- so why bother.
Other more conservative manufacturers may not accept either multigrades or
synthetics.
David
----- Original Message -----
From: "Karl Denninger" <>
To: "Eric Thompson" <>; "LIVE_ABOARD"
<>
Sent: Saturday, November 02, 2002 10:26 AM
Subject: Re: lv-ab: Two stroke diesels
> No, 2-strokes have the same kind of crankcase as 4-strokes when it comes
to
> diesels, and do not (intentionally) burn oil.
>
> The problem is that 2-strokes REQUIRE straight-weight oils. The reasons
are
> design-related, but they all have this requirement - and its absolutely
> inflexible.
>
> They also do intentionally consume some oil by design, and there is a
> sulfated ash spec - if the oil doesn't burn cleanly enough you get valve
> deposits which eventually can trash your valve sealing capability.
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