Expert: Skip Bollinger - 10/1/2006

Question
I have owned a 1991 Buick Park Avenue Ultra since new and have always used Mobil One oil in this vehicle. The past few months the oil pressure has dropped to where, once warmed, the oil pressure is in the danger (red) area. I have had the oil pump changed with no obvious change. I love this car and it still looks great. It has 278,000 miles. Should I just let it go or can something be done short of redoing t engine.

Thanks for your response.

Answer
John,
  Please bear with me for a minute, Okay? I'm a Parts Professional, NOT a Tech or Mechanic. I have been pushing parts 32 years and have learned a little during that time. With that being said, let's begin.
  Firstly I'm guessing the engine is a 3.8?? I'm sure it is but you didn't say.
  Secondly, you said you had the Oil Pump replaced, correct? Did you do it or did you have a Mechanic do it? Was the engine making noise or were you just going by the gauge? Before the "pump" was replaced, did anyone hook up a mechanical gauge to the engine to make sure something isn't wrong with the gauge in the dash OR the sender on the engine?
  The problem Buick has with this engine is the oil pump is not normally replaced, it is rebuilt. The "outer housing" of the pump is the timing cover. When you rebuild the pump, all you replace are the rotors and shaft within the timing cover housing. IF the timing cover is scored, you can rebuild it a hundred times and still have the same problem.
  Before you think about dumping the car or getting another engine, answer the above questions for me. Let me know what the Mechanic says about checking the oil pressure with a mechanical gauge. Get back with me, Okay??
  Skip
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