[Alan Roehrich]

That is why I suggested a look at the pump. In an engine that old, it is possible that the oil pump bypass spring is bad.

Yes, the gauge too is a possibility. I did not mention it and should have. I always check my gauge right after I check my oil and filter if I have an oil pressure problem. I need to remember not everyone does.

Speaking of oil filters, I suggest using either a long Wix racing filter, or a long K&N filter. By long, I mean the 1 quart filter. Oil filters have been known to cause that problem. I've even seen it with what used to be good filters, the AC PF1218 included. The only AC that may still be good is a PF2232 Duramax filter, but I'd check to see before I used it, and it will be the same price as a K&N or Wix Racing, and you'll know what you have then.