Buy time is likely going to be like the middle of next week though.
As for need a T-stat or not, I mean its better to have one than not, however, I cant honestly say how important it is. There are a LOT of people running oil cooler kits that dont have T-stats and I have yet to see anyone having a problem with it. So I dont know that its that vital. I would certainly say there is no real danger. You shouldnt be firing your car up and ripping on it 30 sec later anyway
There are some people who argue that a T-stat is a not a good idea as it corks off the oil inside the cooler, allowing it to congeal (sp?) and making it harder to circulate when it DOES open, also promoting the formation of sludge in the core.
I can see points that seem valid on both sides of the arguement.
However, I cant get past the fact that SO many people run oil coolers with no thermostat, and dont have problems. Remember, the factory "oil cooler" is also an oil pre-heater. So the oil is still going to get brought up to temp fairly quickly regardless.
Now, if you lived in Fargo and it was super cold, yeah I can see it being an issue, as on your daily commute in -10deg temps your oil would never reach operating temp. But this is Texas