You'll only loose a few drops. I do suggest getting this sensor from the dealer. Redesigned set points and reliable. The aftermarket ones are inconsistent and can give false warnings.

Dennis,
From my phone.
________________________________
From: Kevin Duvernay<mailto:kduvey@GMAIL.COM>
Sent: ‎3/‎5/‎2015 10:51 AM
To: vanagon@GERRY.VANAGON.COM<mailto:vanagon@GERRY.VANAGON.COM>
Subject: .9 bar oil pressure sender replacement

I'm swapping out my motor mounts tomorrow. While I'm there I'm also going
to replace the #2/4 header. If that goes smoothly, I've also got a new
water pump along with all new coolant pipes/gaskets and hoses (its
basically the last bits of my complete cooling system overhaul!)

Anyways, I figured while I'm there doing all this I minus well toss in a
new high pressure oil sender (the grey one, .9 bar). What I'm wondering is,
is it possible to do this without loosing too much oil? I JUST changed the
oil out to some really expensive Redline synthetic stuff, would hate to
waste any of it...

Also, anything else I should address while I'm back there?

Kevin