Three problems related to engine oil leaking have been reported for the 1998 Audi A4. The most recently reported issues are listed below.
The vehicle developed a severe vibration in the front end. The upper, lower suspension arms and the tie rod ends were replaced. There was a severe oil leakage observed coming from the engine during acceleration. Oil was found in the spark plug cavities and the spark plug wires protective sleeve was brittle due to high engine temperature.
Car was serviced for an oil leak and what the mechanic found was the ball bearings oil passage seals were leaking from the front of the cylinder heads. Repair would be $4,000 for parts alone. Labor would be additional. Car is less than 5 years old.
I discovered a significant engine oil leak in multiple locations at 50k miles.