Any could explain why H2's use 187F thermostat but the engine normal temp is 210F???

Can I install a 160F thermostat or a bigger radiator is a better idea?

 

first 210 is just fine, supposed to run 200-210, havent hooked scanner to my h2 yet but i found on other gm's temp guage read a few degrees higher than scanner said

 

The thermostat temp is just so you can determine when it will begin to open to allow coolant to circulate from the radiator into the motor through the T Stat. Most common T Stats will not be completely open to allow full flow until appx. 15-20F above their rated temp. So, add 20F to your 187F T stat and you get 207F, I'd say working exactly like it is supposed to.

Moving to a lower temp T stat just slows down how quick your motor reaches full operating temp, then places more cooling burden on the radiator. Modern GM vehicles were designed to run at a sweet spot of 195-215F (depending upon model) for emissions efficiency as well.

 

Update...

Recently the 160F thermostat was installed with new GM coolant. During normal driving the engine temp was less than 180F. As soon the A/C was on, the engine temp goes to 197F sometimes 200F. But when the A/C was turn off it return to the 180F range.