I asked an Audi tech about the same problem on my now long gone 1984 5K and he said to use a pint of Marvel Mystery Oil in the next oil change. I did it and it worked at a mileage of about 75k. Don Scott Past Audi related autos: 80 Audi 4K, 83 VW Quantum, 84 5KS Present: 89 0.1K