Just started driving my 2001 S55 AMG with 66,000 miles, clean car, been manintined at dealer since production. Bought it few days ago. I am not familiar with the temperature gauge on these monsters. It started in the morning with no issues, began going up gradually, and then when I got into traffic and was about to get to work it went up over 80, didnt reach 100, and sometimes it moves few milli meters up or down depending on my driving. What is an ideal temperature for the needle to be pointing at, on average?