90deg C has been the normal operating temp for years. Thermostat openning is commonly 87 deg. It is rare or defective to see cars running at 80deg. It is probably more common to see cars running at 100deg.

Higher efficiency is derived by higher operating temps, be thankful you aren't driving a BMW. BMW uses a electrically controlled thermostat following what is called "Map Cooling". Because deviations are great naturally, BMWs that have a temp gauge are really idiot gauges as the needle stays in the center from 170deg to 230deg F with no movement.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician