1992 Dodge Stealth burning oil and low pressure

My wife's 1992 Stealth ES has a problem. A couple weeks ago I was driving behind her and noticed a small amount of bluish smoke coming out of the exhaust. It took about two quarts of oil to top it off when we got home. I changed the oil and filter that weekend. A few days later she called from work saying that the car had billows of smoke coming from it and the oil pressure gauge was less than one-quarter. Again I followed her as she drove to her appointment. It was embarrassing there was so much smoke.

Working on it this afternoon the oil level was fine. I started it from dead cold. At first, oil pressure was normal and there was no perceptible smoke. When the engine warmed up, the oil pressure dropped and the smoking started. As RPM's went up so did the oil pressure. Dropping back to idle, the pressure dropped with it. The three spark plugs that I could get to had black stuff around the bottom of the outer ring, but the center part was clean.

The car is a 1992 Dodge Stealth ES with 117,000 miles, 3 litre V6, automatic transmission, with no modifications. She drives it mostly around town and never runs it hard. Please tell me this is easy and inexpensive. I do most of the work on my 1987 Pathfinder, but we'll take hers to a mechanic we trust. We just want to know what's likely wrong. Thank you for your help.

Monte B. Carroll Nashville, Tennessee USA

Oil pressure changing with different RPM's is normal. If the oil pressure is constantly reading lower than when the car was new, that's a problem. It could be a failing pressure sensor, but most likely it's worn engine parts, like your bearings. If the oil pressure stays within the normal range, at idle, then this is just normal engine wear. In the old days, I would check to see if the rings or the valves were failing, by doing a compression test on each cylinder, and recording the reading. I would then pour a table spoon of engine oil in each cylinder and do another compression test. If the compression went up significantly, then most likely the rings are worn. If the pressure remained about the same (remember normal engine wear will cause the rings to leak a little) then it was most likely bad valves. Another test would be to follow behind the car and note if there is a change in smoke output when she accelerates quickly, then takes her foot off the gas pedal. If there is a sudden puff of smoke then your valves have a problem. If memory serves me correctly, didn't Dodge engines around this time, have a problem with valve failure.

Ray