First test drive done (without the plastic undertray, so that I could inspect things easier). It was a relatively tame drive, with stops about once every two blocks to pop the hood, check fluid levels, stare under the car with a flashlight, etc. I'm paranoid
Anyways, nothing leaked, everything worked fine. I got in some harder acceleration runs a few times near the end of the drive, all was smooth. Oil temps are definitely going to be way better. It warms up a lot slower, and stays a lot lower. Seems to stabilize at around 195 when cruising around at night now (which is about what our coolant stabilizes at isn't it? doubt that's a coincidence), although it takes its sweet time getting up to that.
No serious oil-temp-stress testing tonight though. I want to go through testing the car at this point in stages so that I can hopefully catch any small problems without them turning into catastrophes
It's worth it to avoid a $10K engine bill or whatever it is if I blew out a line during a hard driving stretch.