Originally Posted by bluestone
Cool, so seems like oil pressure shows more of what's going on. I guess 30 min highway commutes or 3-4 hr roadtrips don't count as prolonged stress? I really only need one gauge right now, have an empty spot on the autometer-style dash gauge bezel.
oil pressure gauge only gives an indication of temp in the sense that you can tell when the oil becomes less viscous and the idle pressure drops from 100 PSi down to 25 psi or so.
HOwever, the oil temp could be at 100, 250, 300 degrees and you wouldn't know it from oil pressure. Also, when I had both gauges, i noticed that the oil pressure at idle drops to 'normal' well before the oil temp actually reaches 100 F, warmed up.
I think oil temp is more useful in that if you see the temp creeping up, you can stop and check things out. Have you lost oil level ?
I once did, through a bad gasket on the drain plug. I could see the temp getting slowly higher than normal. It gives you chance to look for a problem.
If you see your oil pressure has bottomed out, then what are you going to do ? Rebuild the motor ?
If your car has hundreds of thousands of miles on it, then oil pressure might serve as a good indiator of how long till your going to need a rebuild or to let you know that you should switch to a heavier oil.