*EDIT* Sorry - I'm an idiot <img src="/forums/images/graemlins/drunk.gif" alt="" />.

The 85psi mark is the half-way mark, correct? There is a small "dot" (.) at about one-quarter of the guage (about one-half of the way to the 85 psi mark). This is where I usually idle (say ~40-45 psi(?)). Under acceleration, the oil pressure will usually increase a bit (say to about 45-50 psi).

Your psi sounds about normal on warm-up, but does sound low when warm (compared to mine). I'm assuming you've checked the oil level and it's spot on...did you try a different (oversized) oil filter? Could the oil pump be on its way out (off the top of my head, I'm not sure what the symptoms or checks for this might be)?

I'll have to check my Hanyes and shop maunual ...

To pull a code on your '94 I think you can jump two terminals with a wire or paperclip (works for my ABS; I have to use a code reader for my OBDII). Do you have a Haynes or Chiltons? I think they cover reading the codes in there (Emissions or Engine section I believe).