From: "Christopher D. Thompson" Subject: Re: 96 Ram 1500 - 318 - Oil light Date: Sunday, March 09, 2008 5:11 PM
How often has the oil been changed? regularly? as in every 3,000 miles? put a manual gauge on it and run it for long enough to get it acting up, if the manual gauge shows a problem then drop the pan and look. i suspect you will find sludge particles floating around in the oil pan, these get picked up in the oil pump's pickup screen little by little. then you find a dropping or erratic oil pressure. most common is the dropping oil pressure. If you find sludge your best course of action is to replace the engine assy. the next best would be to clean the pan, replace the oil pump and pickup tube then hope you can last a while before enough of the sludge up top gets dislodged to start causing you problems again.
When i was working on cars i replaced more than a few engines for this very thing.
another guess would be that you have a leaking oil pressure sending unit. I've seen them leak into the plastic housing and after its warmed up good give all kids of erratic/wrong readings before again this can be proven with a visual inspection and mechanical oil pressure gauge.