My car started making a funny noise last Thursday (car makes new noise, but seems to drive totally normally). I had a loose belly pan where all screws have fallen out, but I was able to secure back two ones since they were still there. Sound is still there and now my engine really sounds like a diesel engine. I think it might be a bad lifter because of dirty oil (not sludge). Last oil change was Mobil 1 0w40 about 9000 miles ago. Is it safe to drive car around town till I get it evaluated, or is there risk of causing damage to engine by doing so? 1999 Audi A4 1.8 liter Turbo Quattro manual (slightly less than 53000 miles) EDIT: if I had a problem developing with turbo, would I see performance difference (i.e. car wouldn't drive normally)? EDIT #2: And can I add an additional quart of oil as a temporizing measure? (is it possible to overfill an engine with oil? last oil change I think they used 4 quarts).