Oil Pressure 85/86 1.6 TD Jetta

Hi, Tape works on the light but you'll need tape on the ears to drown out the buzzing warning sound. Just kidding, what weight oil are you running? I have an '85 Golf with similar symptoms. My oil pressure light and buzzer went off during sustained moderate driving when it was warm--i.e., city driving at 55-60 km/hr (that'd be like your 30-35 mph). Revving the engine would solve the symptoms for a short time. I thought it was a low oil pressure issue. The original car manual spec'd 10-30W oil. When I mentioned the problem to the fellow at the independent vw parts store he said the current spec is 10-40W in that vintage of auto. I tried 10-40W and the thicker viscosity did the trick, we haven't heard the buzzer or seen the light since. Try that, it's an easier and less expensive fix than rebuilding.

-Tony