Engine Mechanical problem
1989 Ford Bronco V8 Four Wheel Drive Automatic 127000 miles
After warming up, at idle in drive, (around 600RPM) the oil pressure gauge jerks lower and lower towards no pressure. Each time the gauge hits the red zone, the red " Engine" light comes on. Shifting into neutral or lightly pressing the accelerator to get the RPM up to 700 or so brings the gauge back to normal and solid. If the pressure is allowed to go to 0, the engine will stall. Starts right back up again. Truck is well maintained. Runs very well until this starts. Any ideas? Been running Mobil 1 5W-30 in it for about 10,000 miles. This problem just started. Truck recently had new water pump, intake manifold gasket, valve cover gaskets, timing chain, external fuel pump, relay, and fuel filter replaced. Thanks!
Ok it sounds like the engine is getting tired and will be in need of replacing or rebuilding soon. The oil is good when cold then drops when warm correct? If this is true it is because the cam bearings are bad. Now what I would do if you need to save you some time before having to rebuild the engine is go back to standard motor oil and use 10w-30 and then add a quart of Lucas engine oil stabilizer this will keep the oil at a better viscosity and buy you some time.