No thermostat in 96 OBW

I have had overheating problems with my 96 OBW with 178,000 miles. The radiator was changed and unbeknowst to me the thermostat was not installed. I will noted that I had added "Water-Wetter" to the radiator. It has been running well, with the temp gauge at the 8:30 position. I does go up to the 11:00 position, but it will drop down. I decided to change the thermostat; in fact it was a Subaru OE theromstat. After its installation, the car overheated within a mile. I brought it back to the mechanic, was told there was no thermostat to begin with, and had it removed. New anti-freeze/coolant and new "Water-Wetter" was added and it's running as it was before it went to the mechanic. What can I expect with the car running without a thermostat into the winter? Thanks

My Liberty and 99 OBW both have thermostats, so It's difficult to see why a 96 wouldn't. If I'm wrong I apoloigise, but IME every liquid cooled auto engine in the last 50 years or so does.

Lots of people take the t/stat out as a cheap quick fix for an overheating problem rather than find the source of the overheating. Makes the gauge behave ok but water being lazy it also lets the coolant run round and round just the front of the block & the radiator, so the back of the engine gets proportionally hotter, often with no indication until something breaks. Good recipe for a blown head gasket, especially in engines with siamesed bores or boxer configurations. Suggest try & get 'em to fix it or find another shop. Cheers