Hauge:
the simplest solution (I think) would be to use an analog oil pressure sensor
I hadn't thought to use an automotive oil pressure sender... So something like this perhaps?
http://amzn.com/B00029JXMA
This is where I'm rather unsure about how "most" pressure units work. Are they linear output, such that getting a handful of readings from it I can map the rest out pretty easily? Because I'm not finding a spec sheet for it, and I wouldn't really expect to find one for a cheap generic unit like that.
Thoughts? It certainly borders on cheap enough to play around with, but I don't like burning $20s either if someone can tell me that's all I'd be doing 