I think the 150* is steep, really, I'd say anything over 120-130*F would be more than enough. You don't want it to take too long to get up to that temperature though. I've been tossing around the idea of getting a thermostat type thing. Something similar to this:
http://www.transmissioncoolers.us/708-4739P6.html

They have them built into oil adapter type stuff, so I'd have an external filter, thermostat, and temperature sender.