I was not happy with the response of the mechanical oil pressure guage I
installed in my '85 camper.  Particularly in the winter time, the delay
made it almost useless.  I found a cheap guage on-line from (don't laugh)
JCWhitney.com for $17 which included the sender.  I figured for that kind
of money, I'd give it a try.  I am happy with the results.  It comes with
an illuminated 0-100 psig (0-7 bar) 2" gauge and a sender that also has a
10 psig switch built in to it.  I installed it the sender about 3 feet away
from the engine using the 1/8" copper tubing I had run front for the
mechanical guage.  I kept the VW sender that was already teed into the
block.  I ran two wires from the sender to the dash and mounted the guage
under the left side of the dash.  Next to it, I mounted an amber light that
is hooked up to the switch on the sender.  It works just like the stock
unit--lights up at start up and goes off when the engine is running--only
it is set a few psi higher.  You need a 12V supply and a ground at the
guage.  You could just remove the stock switch and use the factory wire to
the sender if you wanted.  My oil pressure is little low so I am using the
amber light as an early warning device.  The plastic mounting cup that I
ordered is kind of cheap looking, but I think the guage is hard to beat for
the money.
                                                   Jay