The Stovebolt Site Forums The Shop Area Engine Shop Oil pressure on 250 C I in line six

Can someone tell me what the oil pressure should be on a 1975 Chev 250 CI in line Six.

Oil pressure will vary according to temperature, bearing wear, and the viscosity of the oil. A good-condition engine running 10W-30 oil will probably start out cold at around 40-50 PSI and drop to 20 PSI or so at hot idle. The switch that turns on the idiot light oil pressure warning contacts at about 7 PSI, so a lot of people who don't run an accurate gauge have no clue how low the pressure actually is at times. "The light's out, it must be OK, right?"

Actually, it's theoretically possible to lubricate an engine with zero oil pressure- - - -as long as all the bearings receive oil at exactly the rate it's being leaked away back into the crankcase, the pressure on the gauge will be zero. Any oil pressure at all indicates the engine is getting more oil than it needs.
Jerry

Thanks jerry. This engine is in my 53 so the original gauge and no idiot light. Pressure is around 28 to 30 PSI when on the road. I can now assume all is well.

There is an old rule of thumb:

10psi for every 1000 rpm as the minimum. ( hot engine) ( modern full pressure system not a 216)

Example
1000 rpm = 10 psi

3000 rpm = 30 psi

These are minimum values, obviously 10w vs 30w would make some differences. But if the engine does not meet these minimum value start looking for issues.