oil press warning

Henry A Harper III hah at alumni.rice.edu
Sat Sep 4 15:41:22 EDT 2004

> >So the question is...  Will over pressure tip off the warning?
> There are two pressure sensors--low and high. So, yes, it can react
> to excessive pressure. But although I've often seen 5 bar briefly
> during warm-up, I've never had the pressure warning. The ECU
> considers the combination of RPM and pressure (and perhaps engine
> temp) to decide on whether to issue a hi/lo warning. The "critical"
> RPM is about 3K, I believe. I'm sure some lister knows the exact
> parameters for oil pressure warnings.

The "high" pressure sensor is actually to check for oil pressure *below* a
certain level at a particular RPM - 1.8bar at 2000rpm or something like
that. It's not an overpressure sensor.

> >I really get the feeling this is a gremlin but maybe that is just
> >wishful thinking.
> >I'm running 20w 50 dino oil.
> The 20W 50 weight could be an issue I suppose--why such a high
> viscosity range? I'd guess a defective pressure sensor (not uncommon)
> is the more likely culprit--something I've escaped so far (knock on
> zebrano).

Umm...20w-50 is the recommended summer viscosity, and it was a "hot day".
According to the little chart in Bentley. 10w-40/10w-30 should not be used
at ambient temperatures over 60F, if the chart is to be believed. We don't
have newfangled engines that run on 5w-30 year round for 10k miles between
changes and get sludge ;)


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