[Nevadan]

It's filled with something else, wax maybe, hence the name, I'm not real sure what but it's not antifreeze.

Excellent idea on interchanging the pins. On mine the pin diameter is a little different so I'll need to look at some other thermostats to find one that matches.

I've done further testing and will do more today.

Heating the thermostats in oil rather than water allows me to keep the temperature more consistent and have a longer working time.

In the above photo the original "waxstat" from my oil diverter valve will open at around 220-230 but doesn't retain enough resistance to overcome the force of the return spring; I can just push it back closed with pliers, so it's not working.

The innards of the 1.6 thermostat work perfectly, it opens at a little cooler temp than I want for the oil cooler but I may use it anyway. I think it would work excellent for the IP waxstat.

More to come