Synthetic oils in a 1984 5000s

[xmishx]

I just put in some synthetic oil, and a fresh filter in a recently acquired 5000S. Though the car was running fine before the change, now I'm getting a oil warning lite and temp warning lite. I have plenty of oil in the car and the temp gauge in the car reads acceptable. Any clues? Help! Thanks, X

[0fframp]

Any clues? Yeah, probably the bearings or the oil pump is shot. Hook up a cheap mechanical gauge just to make sure that it is not the pressure sensor. I think that the previous owner put in 20W50 or some additive (like motor honey) to build up oil pressure and quiet down noisy bearings. When you drained the oil you replaced it with a thinner synthetic which is easier to pump and lowers the pressure. There is also a pressure regulator mounted on the pump and is easy to access, maybe the spring broke or weakened.

[kakarot]

unscrew filter put a can under it crank the engine to get oil out and put higher grade oil in their. find 25W-60 or 25W-50. or put addictive to increase the oil grade, or just change it again for higher grade. do that if in the morning when you start the car the light is not on for oil pressure.
else you have a bad spring, or and pump.