[Vwdiesel] Risks of straight weight

Wed Oct 5 03:38:31 EDT 2005

I'm not an oil chemist, but I've torn down my share of engines.  Wrong grade
of oil expresses itself mostly as leaving  a really dirty engine interior.
Specifically, the oil that is not diesel rated has to be changed more
frequently to remove the soot that accumulates in the oil or sludge builds
up on the interior of everything which just can't be good.in the long run,
and soot in the oil causes wear when the oil can't hold any more. I've seen
a half inch of black goop on the interior of a valve cover of a highway
tractor from running a poor grade of oil.
Biggest difference in oils is the soot handling characteristics.  All my
stuff that runs Rotella T has nice clean shiny interior parts on teardown,
including the service truck (gasser)  that I just freshened the motor on
this fall. Hardly any need to have the block tanked before rebuild, and
valve covers that had been on for 300K kms were clean and shiny inside.  You
do not see that with engines that run the cheaper store brands of oil.
In winter I run a semi synthetic shell 0-40 It's turbo diesel rated, works
well. The biggest factor in reduced engine longevity is oil starvation on
cold starts. Run good oil,. engine lasts a long time. Don't run good oil, it
doesn't. The right oil makes a huge difference in the cold.  Cranking speed
is a big factor in cold starts, and the proper oil will make a huge
difference.
-James

-----Original Message-----
From: vwdiesel-bounces at vwfans.com [mailto:vwdiesel-bounces at vwfans.com]On
Behalf Of Area31 Research Facility
Sent: Tuesday, October 04, 2005 11:13 PM
To: vwdiesel at vwfans.com
Subject: Re: [Vwdiesel] Risks of straight weight

Do any of our oil chemists know what the dangers might be running non-diesel
rated, ordinary 10W30 motor oil in say a 1.6 Jetta TD in cold Canadian
winter weather 0 C (32F) to -25C maybe -30C ?

What is different about a lube oil formulation for a diesel engine than for
gasoline engines anyway?

Rob
Energy shortage?  Impossible!  In most of the developed world, the exception
being England, electrons literally swarm out of the ground.

----- Original Message -----
From: "Gerry/Joy Wolfe" <gjwolfe at telus.net>
To: <vwdiesel at vwfans.com>
Sent: Wednesday, October 05, 2005 1:03 AM
Subject: Re: [Vwdiesel] Risks of straight weight

> To quote Bentley...
> A2 diesels can use 15w40 about 0F thru 85F, minimum CD quality for a TD.
>
> My understanding is that (say for a 15w40 oil) the base oil would be a 15w
> and would have viscosity improvers to make it look like 40w oil when
really
> hot.  Generally, the closer the numbers are, the fewer viscosity improvers
> and the more real live lubricating stuff.
>
> A question for the experts:  What percentage of the total volume of oil
> would viscosity improvers have to be to make a a straight 15W oil look
like
> (15w)40 oil.  1%???  60%???  If it's only 1%, then there is still 99% of
> lubrication available in the mix.  If 60%, then I would guess the oil
would
> only have 40% of the lubricating capacity of a straight 40W oil (ignoring
> any lubrication aspects of the additives).
>
> Far as changes are concerned, oil doesn't really "wear out", but the
> additives do get chemically neutralized and the soot accumulates.  IMHO,
> 'specially with a diesel, using a "cheaper" oil (meeting/exceeding the CD
> requirements) and changing it more frequently is better than using an
> overkill synth and not changing it as frequently.  This proved out to me
> recently... had to have a head gasket changed at 275K km and consequently
> had the head overhauled and a re-ring... there was virtually no
wear/ridges
> in the cylinder walls, even the mechanic was surprised.  I do changes
every
> 3 months, Rotella 15w40 dyno.
>
> Other hand, synth oil does a better job handling a hot turbo on shutdown -
> less prone to coking i.e. converting liquid oil into solid carbon (doesn't
> lubricate nearly as well next startup).
>
> Just my $0.02 Cdn...
> rgds, g.
>
> ----- Original Message -----
> From: <LBaird119 at aol.com>
> To: <vwdiesel at vwfans.com>
> Sent: Tuesday, October 04, 2005 08:19
> Subject: Re: [Vwdiesel] Risks of straight weight
>
>
> > And for what its worth...What do you folks run, and at what temperature
> > ranges?  I've been running 15W-40...mainly because that's what I can
find
> > that's diesel rated... in a hurry at the station.
> >
> >
> >  I've always run Cennex 15W/40 year round, even when it's -20F.
> > That doesn't happen much anymore but other than slighlty slow
> > cranking on the COLDEST mornigns it does fine.  Pour point is
> > the real thing on cold starts and it has a lower one than a lot
> > of "thinner" oils.
> >    Loren
> > _______________________________________________
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> > Vwdiesel at vwfans.com
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> >
> >
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