I have a 92' formula with the l98. After the last oil change I noticed the oil pressure had dropped from what it was before. I run the same Mobil 1 10w30 and same Wix filter as before. It just seems to be way low at idle around 20 psi where it would never drop below 35-40 and on gas it's around 40 where it was always 50+. Any ideas?

Thanks,
Danny

 

Replace the sending unit.

Divide the situation into, do you have an OIL PRESSURE problem, or an OIL PRESURE GAUGE problem.

And before somebody comes in and says to buy a mech gauge and check your dash gauge against that, here's the sequence of events that leads to:

1. Notice dash gauge reads weird
2. Spend $$$$ on a gauge
3. Spend a whole afternoon finding a place to plumb it to, getting the plug or whatever out of that hole, installing the line or whatever for the new gauge
4. Crank up car, discover that yes, the OP is fine like always, but the gauge is wacked
5. Now what do you do
6. Remove all the aftermarket gauge crap
7. Dink around variously trying to figure out why the gauge reads weird
8. Post on the Internet some more
9. Somebody that's been through this about a hundred times replies that the gauge itself virtually never fails, and that if the motor isn't in some kind of low-oil-pressure distress (knocking, valves ticking, oil looks like black gunk on the dipstick, etc.) then there's probably nothing wrong with the actual oil pressure, and that the sending units fail ALL THE TIME and they're CHEEEEEEEEP
10. Go to the store and pick up the SU for like $15 (a quarter the price of the aftermarket gauge)
11. Replace it
12. Gauge now reads fine

OK... so right now, in real life, you're already at step 9. Your pop-quiz question is:

What value would you you get out of going back and screwing up by putting yourself through steps 1-8?

While just randomly throwing parts at a problem isn't usually the best thing to do, there are times that it is. This would be one of those times. Just go ahead and change out the SU and be done with it.