You supposed to use 20/50.  Try that and then complain, I guess.
Zoltan

----- Original Message -----
From: "pickle vanagon" <greenvanagon@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, November 27, 2011 7:27 PM
Subject: Oil pressure light in 1.9l at idle

> On our returning-home-after-thanksgiving drive, we had some scary oil
> light
> flicker.
>
> Here are the details:
>
> Engine has just a little over 100k miles on it.
> I typically run Mobil 1 15w50 in it, but shortly before this drive changed
> the oil to Castrol Syntec 5w50, hoping to achieve better lubrication
> during
> cold-starts in the winter.  I used a Mobil 1 filter (which I've used
> occasionally before, though now it was replacing a Fram tough-guard).
> Flicker definitely seemed related to oil pressure.  That is: it only came
> on after driving fast for a long block of time, and then letting the
> engine
> drop to idle.  After I first noticed a flicker happen once and confirming
> the oil level was fine, I tried this experiment several times and could
> often get some flickers out of it, although not always.  Raising the
> engine
> rpms *at all* would completely kill the flicker.  I couldn't give it even
> a
> tiny amount of gas and still have flicker, even after a long run.
>
> Further mitigating factors:
> We have an auxiliary battery setup with heavy gauge wire coupling the
> batteries via a Stancor relay.  The auxiliary battery is a year old or so
> and so almost certainly in worse condition than the starter battery, since
> that never gets drained at all.  I have the batteries set up so that a
> switch can be used to kill the stancor relay when driving (or force it to
> be engaged when the engine is off).  Anyways, with the stancor relay
> disabled, I wouldn't get any oil light flicker, as the engine was idling
> high enough to avoid it.  The flicker was only happening after a long fast
> run *and* at especially low rpms, which would only happen when both
> batteries where being powered by the alternator.
>
>
> Obviously I find this all pretty scary!  I figure the first step is to
> figure out what my oil pressure is at various operating speeds and
> temperatures.  So I've ordered parts to install an oil pressure gauge.
>
> I realize there's a lower threshold (blue) .25 bar switch that VW
> recommends to replace the existing .3 bar switch, which would likely
> eliminate my flicker,  but right now I'm just worried this is an
> indication
> of deeper problems.  I've ordered one of these switches anyways just in
> case my current switch is bad, but the behavior I'm seeing rules out a
> wiring issue I think, and I haven't actually heard of anyone having an old
> switch that was still responding, but just at too high a pressure (if
> anything I would expect them to fail in the other direction.)
>
> I also realize the switch to castrol 5w50 may have been what made the
> difference.  But I'm reluctant to throw back in some 15w50, have the light
> go back off, and then just call the problem solved... I mean, I shouldn't
> really be that close to the edge of triggering the switch right?  Or
> should
> I be considering it likely that the 5w50 really was just too unstable in a
> 1.9l (which has no oil cooler) at high speeds?
>
>
> I'll be grateful for any advice... wow, I hope this engine isn't giving up
> on us!!  I was planning on getting a lot more life out of it...
>