Oil pressure; is this normal?

[Frans Veldman]

Hi,

Recently some people here advised me to install a mechanical oil pressure gauge after I had some incident where I lost the oil. Now I have installed a mechanical gauge, but I wonder if my readings are normal.

The 318 is stock (apart from headers and 4-barrel carb), it has fresh 10W40 oil in it. Temperature here is just above freezing.

Cold engine (first 5 miles): 20 psi.
Warm engine, loaded, above 750 rpm: 40 psi.
Warm engine, no load, above 750 rpm: 45 psi.
Warm engine, idle, 500 rpm, 25 psi.

The cold engine figure surprises me. Maybe this is because the oil is not flowing so easily through the oil filter and cooler when it is too cold?

Then, there is definitely a difference between having the engine loaded and unloaded. If I release the throttle, the oil pressure goes up immediately with more than 5 psi. Does this indicate anything? Or is this how it is supposed to be?

Note that my idle is pretty low, if I increase the rmp to 750, I get 40 psi. I guess it does not harm the engine if I let it idle with 500 rpm with just 25 psi, right?

Never an electrical gauge for me anymore! This mechanical gauge shows indeed what is happening!

Thanks for your comments,
Frans

[Marc]

Maybe it's working air out of the line?
I would think there is nothing wrong with the other pressures....

[HOLESHOT]

the oil pressur cold should be easily 50 with a stock pump and drop off.Id look at air in the line since it will compress while a liquid will not.Bleed line into a rag while engine hot from gauge back to see if it changes.Why the 10x40 all you need is at most 10x30 synthetic which flows better and reduces hp loss.Is this pensoil that you run?