Which oil pan do you have?My 200F thermostat came in two pieces as well, and I thought nothing of it and pushed the pin back in and installed it.
I also am using an oil temperature gauge, and after 10-12m of moderate driving (RPM around 3k - 4k) oil temps come up to just under 180F. After pushing the car harder (staying on the small cam) oil temps come up to 185F or so after another few minutes.
After some big cam fun time, oil temps can approach 200F - 205F but never really pass that point on the street, and oil temp comes back down to 180F pretty easily.
I assumed this was normal oil temperature behavior, even with the 200F thermostat, but after reading recent posts maybe it's not normal?
My car is a 2005 touring pack Elise, so I think it has dual oil coolers but I haven't checked to be sure. Still learning.
I've heard sometimes people get the 185F thermostat instead of the 200F unit by mistake, as in they get sent the wrong thermostat, so that is a possibility as well I suppose.
Might as well throw in a 185F thermostat on the next oil change to see if temperatures change much.
Where are you measuring the oil temp?
What are the outside temps?
As shown in the graphs above, big alloy pans cool almost as well as the oil coolers
180 - 190 is the pretty normal temps fro me with 180 thermostat and standard pan in most conditions. Goes over 205 in hot weather and spirited driving