I was doing some datalogging / engine data collection today, and decided to calibrate the temp bars with the actual engine coolant temp.
Here's the results
Bar2 comes on at 158 * F
Bar 3 comes on at 185* F
Bar 4 comes on at 212* F
Bar 2 will show from 158 to 184* F
Bar 3 will show from 185 to 211* F
Bar 4 will show from 212* +
I didn't try to find a 5th bar
I also didn't record for bar 1 but based on the c* spacing of 15*C each bar is calibrated to, I would expect it to be from 131* F to 157*F
In all the years I've been on this forum, I've never seen this information published. Hopefully we now have a better picture of what those silly bars

mean in the real world.
Steve