Low Oil Pressure
My 92 was experiencing this anomaly when I purchased it from the original owner and during the test drive, he placated my concern by showing me receipts as proof that he had the problem professionally investigated.
At any rate, after the next scheduled oil change I rejoiced when the low oil pressure at idle syndrome went away. However, very close to the next scheduled oil change that familiar ‘ding ding ding’ signaling low oil pressure began to occur - but only occasionally.
Ya, this has been some helpful information [he rolls his eyes]. However, seriously, it may not be as complicated as some previous posts suggest - you might be fortunate like I was by simply using different oil.