Fw: [Vwdiesel] Amsoil

Dana Morphew kadm at pugetsound.net
Tue Jul 22 17:39:18 EDT 2003

Why does oil have a time-determined change interval in addition to the
mileage/kilo interval?  I have a hunch that either the anti-oxidants are
presumed to be exhausted after X amount of time, or the acid formation
from moisture condensing in the sump has depleted the anti-acid
additives in "such and such" amount of time.  Does anyone know for sure
though?  If I've driven my vehicle 1500 miles in six months of "normal"
driving, all trips being long enough to thoroughly heat the Delo 400
15w40 oil and evaporate any water that was present, and only one trip,
60 miles long, made each week, are the respective additives going to be
too low to safely continue using the oil for another 6 months when I'll
have 3000 miles and one year on the oil? During this hypothetical case,
1/2 quart was added every 750 miles.

Gerry Wolfe wrote:
> Oil doesn't really wear out.
> It does pick up a bunch of byproducts-of-combustion that can create some
> ugly acids etc. that are offset/neutralized by the additive packages.  I can
> see where overdoses of additives can  counteract this to allow for longer
> drain intervals, and periodic testing can identify when these neutralizers
> have been used up.
> With a diesel, we also have soot being added to the oil.  I suspect these
> are relatively inert, but they are solids.  Unless there were a bypass
> filter, or unless you changed the main filter regularly, these would
> increase over time and no amount of additional additives or testing would
> remove them.  They can't be good for lubrication.
> For that reason, I stick with a 15w40 diesel-specific (cheal) dino oil such
> as a Rotella and change regularly instead of using a more expensive synth
> changed less regularly.

> >   Generally when Amsoil recommendes the long interval for oil change they
> > recommend using their bypass filter.  They don't (or didn't anyway)
> recommend
> >
> > the really long intervals without it.
> >      Loren

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