Over 2bar when running is good. If its below 1bar when hot (oil temp 80°C+) and above idle its sick. Presure will rise with revs and drop with heat of course.
I got mine off an Audi in the scrappy. Its a genuine VDO/VAG part, corect scale for 5bar clock (if your lucky the car might have one of them too), corect M10 thread to screw streight into the engine, and has a built in 0.3bar warning switch (same as lower presure switch, most senders being sold are a different presure) so you can simply fit it in place of the original low presure switch and retain full warning light function, without needing Tee pieces. Best part is it cost vertully nothing, they are fairly pricy new. All I need now is the instrement.