If the "old" thermostat was stuck open or was opening early the temperature would probably stay around 60deg. unless it was really hot outside or you are climbing lots of hills. The thermostat should open at about 80-85deg. which is the normal operating temperature for these cars. Your auxilliary fan would not come on at these temperatures. Unless you are in the 95-105deg. range I wouldn't worry.

__________________
1991 M-B 560SEL Arctic White/Grey 99,000 Miles
1987 M-B 300SDL Ivory/Palomino 229,000 Miles (sold but never forgotten)
2006 Volvo XC70 Blue/Beige
1999 Porsche Boxster Arena Red/Savanna Beige
1986 Porsche 928S Goldweiss/Brown