Are you really running hot? Is the fan coming on more often? My gauge read
low. One day the coolant level sensor blew out of its bottle and  went into
orbit.Upon reentry,when I looked closely at it,I saw a cracked plastic
probe.Was this reentry damage or was this crack there previously? When I
put a new used sensor in the tank, my gauge started reading normal ,again.
This was an unexpected side effect from sensor replacement. I only wanted
to drive again.

Remove the spare tire to get better air circulation.