These thermostats appear to "drift" as they age. When new, my car ran pretty consistently at 90C on the freeway at any temperature. Now it runs at 80C until the ambient temperature is over 70-75. At that point it increases and runs up to 90C as the air temperature increases to 90F or more.

Of course, in traffic it will heat up to about 100C and I know the fan clutch engages from the noticeable fan roar at about 2000 as you accelerate.

The thermostat "drift" to the down side is no big deal.

Duke