Hi Mike
Using a drop of oil is perfectly normal, especially in a petrol engine, most manufacturers say up to a litre per 1000 miles is fine. With an Audi, they aren't overly fussy on the grade of oil used as they can use a a 0w-30, 5w-30, 0w-40, 5w-40 0r 10w-40. Dealerships tend to use a 5w-30 across the range as that's what the newer cars need, so having just one oil to deal with keeps it easy for them. Using a 5w-40 will give the cold start protection of the 5w-30, but will be a bit thicker when hot, so should slow the burning.
Cheers
Tim