I have an A6 Allroad with 2.7 bi-turbo petrol engine and I get a hot burning smell from the right-hand front corner after a short run of some 5 miles. I believe this is caused by oil leaking onto the turbo and beginning to burn off. If I drive some 30 plus miles, the smell is not obvious. How difficult is it to access the turbos? Does the engine have to be removed?