[Vwdiesel] Oil Light/Buzzer

Fri Feb 14 17:24:16 EST 2003

I'm not a tribiologist, and I'm not a oil dealer, so I haven't had the
benefit of their training.  I do have over 1,000,000 miles experience
driving VW diesel cars, and for the longest time, I drove 20W50 nearly
year round.  For about two or three months out of the year I ran 10W40
oil.  And I live and drive in upstate NY, where winters are usually
real.  Well, the snowfall is real, even if the winters are wimpy.

I have never experienced the kind of symptoms expressed in the initial
post except when:

	-there was an instrumentation error (this has been covered)

	-there was excessive clearances in the engine, and the engine was
	high time

	-there was a oil pressure regulation issue (ok, not on a VW, but
	on a tractor)

	-oil was thinned down by large volumes of diesel fuel due to poor
	injector performance

As an aside, I have gone to lighter weight oils, mostly as an experiment,
after hearing many people comment on the tendancies of heavier weight
oils to clog and also to cause higher wear on the oil control rings on
diesel engines.  (It may not be true.)  I mostly used the heavier
weight oils so that I would presumably have better lubrication once the
engine was up to temperature.  I live in a rural area, so I can
be leasurely in getting up to speed on cold days, and until recently,
all my engines were normally aspirated.

In aircraft engines, which are aircooled, generally we run the heaviest
weight oil which supports acceptable starting and warm-up lubrication.
On a summer day, it is typical to startup at a high ambient temperature,
and then climb and operate at a sub-freezing or even sub-zero temperature.
50W straight weight oil works just fine in those conditions.  When temps
are colder we run either a 40W or about a 30W oil (aviation grade 65 to
be precise).  Some of our fleet gets multi-vis in the winter, and that
is because we need to assure effective lubrication at startup, but want
higher viscosity at operational temps.  In the summer, we always run
straight weight (mostly for cost reasons).

So my take is that a 50W (or a 5W50) should be just fine at colder temps.

Having said all of that, it's easy to change oil, and try something else,
but there's also allot of merit in knowing where the oil pressure is really
sitting.  One diesel Rabbit I owned ('79) had an aftermarket oil pressure
guage.  As the car passed 200K miles, and then 300K, I was always amazed
at how low the pressure would go at idle.  Eventually, near the 400K point,
I decided to up the idle, just to keep a little more pressure there.

So faced with the symptoms described, I'd be inclined to hook up a guage,
even temporarily, and get some data points.  I'd also consider swapping
out the sensor, if I had any reason to suspect it.  Or testing it, if
I had compressed air, some fittings, and a guaged regulator.

5W50 oil is thin stuff, and it could be that running 10W40 or 15W40,
things will be better.  I would be inclined to invest time in taking
some measurements.  It would be nicer knowing where I sat.

New thread...for years I used non CD rated oils (availability and cost).
In tearing down a couple of engines from that time, I have found no
noticable difference in sludge (virtually none), varnish (none) and other
accumulations.  Furthermore, on a small sample size of vehicles (we're not
talking a large statistical sample size here), I've had no noticable
difference in condition or maintenance history.  From what I've been able
to ascertain, the greatest difference in the oils (given the brands I used)
is in soot dispersal.

This approach could be characterized as frequent oil changes (2500-5500miles),
less frequent filter changes (normally every other change), and using cheap
oil ($0.99 mobil, quaker state and castoroil).

Anyone else have experience to share in this area?

Oh, now that I have a new TDI, I am running a synthetic 5W40, and at least
initially, changing the filter at each change.  But the interval is
longer, and the engine newer.

Sorry for the long post...I got carried away.

Val

>
> You're reading too much into my posts.  I'm well aware of the benefits of
> multi-grade oils.  But, IMO, Xw-50 (be it 5w-50, 10w-50, 15w-50, or 20w-50)
> is too thick for extreme cold temps.  I'd run a 5w-30, 0w-40 or 5w-40 year
> round up there.
>
> Chris Thornton
> 1991 VW Jetta GL 2 Door 1.6D - 234k miles
> 2000 VW Golf GLS 1.9TDI 130hp/229ftlbs - 76k miles
> Amsoil Synthetic Lubricants Dealer #1098500
> http://www.amsoil.com
> http://texastdi.com/6/ubb.x
>
> ----- Original Message -----
> From: "Drew MacPherson" <drew at scirocco.cs.uoguelph.ca>
> To: "TexasTDI" <TexasVWdriver at hotmail.com>
> Cc: <vwdiesel at vwfans.com>
> Sent: Friday, February 14, 2003 2:00 PM
> Subject: Re: [Vwdiesel] Oil Light/Buzzer
>
>
> >
> > I sincerely doubt that the buzzer is coming on when the engine is at
> > operating temps in the wintertime because the oil is too thick - which
> > seems to me what you were suggesting in your original response to Sandy's
> > post.
> >
> > And although I'm not an expert on oils - I do understand the high
> > viscosity number (the 50 in this case) defines how the oil flows at
> > operating temp (100C I believe?) and the low number (5 in this case)
> > defines how the oil flows at low temps (not sure the temp - is it 10C or
> > 0C?)  This flow flexibility comes from polymers in the oil which react to
> > the temperature of the oil (cold=short, hot=long.)
> >
> > The ambient temperature (extreme cold in this case) has little or no
> > meaning as far as the HIGH number is concerned, because until the
> > operating temperature is reached (or at least the temp. the rating is
> > achieved at,) the oil will be performing at a lower viscosity - and
> > where's the harm in that?  That's why you want a multi-weight oil in the
> > first place.
> >
> > If an owners manual specifies 5W30 for cold weather operation and 20W50
> > for hot weather operation, then what's wrong with running a 5W50 year
> > round?  You get the cold viscocity to start the thing in the winter, and
> > the hot viscocity you need to pump those hydraulic lifters, lubricate the
> > turbo, and keep oil on all the bearing surfaces at operating temperature.
> >
> > Once upon a time we were discouraged from running conventional oils
> > with extreme viscocity ranges (like 10W40 for example) because the
> > polymers were very long and prone to breakdown.  I expect that the
> > miracles of modern chemistry have changed all that with the myriad of
> > wonderful synthetic and synthetic blended oils we have on the market
> > today.
> >
> > Drew
> >
> > On Fri, 14 Feb 2003, TexasTDI wrote:
> >
> > > I read the post and I know my oils.  The "5" part means nothing when the
> oil
> > > reaches operating temps.  The "50" part is way too thick for extreme
> cold
> > > winters.
> > >
> > > Chris Thornton
> > > 1991 VW Jetta GL 2 Door 1.6D - 234k miles
> > > 2000 VW Golf GLS 1.9TDI 130hp/229ftlbs - 76k miles
> > > Amsoil Synthetic Lubricants Dealer #1098500
> > > http://www.amsoil.com
> > > http://texastdi.com/6/ubb.x
> > >
> > > ----- Original Message -----
> > > From: "Drew MacPherson" <drew at scirocco.cs.uoguelph.ca>
> > > To: "TexasTDI" <TexasVWdriver at hotmail.com>
> > > Cc: "Sandy Cameron" <scameron at compmore.net>; <vwdiesel at vwfans.com>
> > > Sent: Friday, February 14, 2003 8:08 AM
> > > Subject: Re: [Vwdiesel] Oil Light/Buzzer
> > >
> > >
> > > >
> > > >
> > > > If you re-read the post Sandy mentions he's running a multi-weight
> 5W50
> > > > synthetic, which is a far cry from 50 weight (which would be axle
> grease
> > > > at the temps we've been seeing lately.)
> > > >
> > > > Sandy's pressure problems are likely stemming from the fact that the
> 5W
> > > > oil is getting too thin at higher oil temp, resulting in a drop of oil
> > > > pressure.
> > > >
> > > > Drew
> > >
> >
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