[Vwdiesel] Oil Light/Buzzer

[Drew MacPherson]

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
>