Hello all-newbie here. I just purchased a 1994 Audi 100s wagon; it has 88K miles. two things I've noticed that I wanted to ask questions about:

After I start the car, when idling and sometimes going down the road, I hear this scraping/grinding sound that sounds as if it's coming from underneath the vehicle. The exhaust system is a little louder than I expected, so I'm wonderinf if perhaps one of the exhaust pipes has loosened and is intermittenly scraping against the undercarriage? Has anyone experienced anything similar?

the other issue is coolant loss. I've had to fill the coolant tank about every 50-100 miles, as the alarm in the center of the dash will sound. I cannot find any evidence of coolant leaking anywhere--there's no water under the hood, no hissing sound, no antifreeze smell. the temperature has not gotten above just over the center mark, and it rises and falls with my speed. Any ideas? I've checked the oil, and have not seen any evidence of coolant mixing with the oil.

Thanks in advance for any advice.