The temp seems fine, although most edge upward a bit from 80. How long does it take to reach this temp? Should be able to reach it in less than a five mile drive at 40-50mph. If it's taking 20 miles to obtain this temp I'd suspect the thermostat as staying open the entire time. Have you ever replaced this item on your car yet?
"Tell me and I will listen, Teach me and I will learn, Show me and I will accomplish, Involve me and I will succeed."
'84 300SD 256,000 Gold on Brown (Mileage Award)
'86 300E 246,000 Blue on Tan