Engine:
350 Chevrolet stock bore and stroke. Not a real high performance piece but has a little bit of cam (hydraulic), dual plane intake and a little port and polish on the heads.

Very low mileage it’s in a 1960 Chevy pickup I just cruise around town in.

Oil pressure:

When you first start it the oil pressure is
60psi.

When driving around the oil pressure is good,
30-35 mph just cruising around pressure is 40-45.

Out on the backroads running 50-60mph pressure is 50-55psi.

My concern is that after a little cruising if you pull up to a stop light or pull into a parking lot to talk, the oil pressure falls to 25psi at an idle.
How concerned should I be about this, and what actions should I take?

Do I have a main bearing going out?

Thank you all in advance for any sort of help or advice about what to do.

My opinion is, that wouldn't worry me. Pretty much what my small block in my roadster did for years turning to 6800.

I haven't driven a street SBC in years but seems pretty normal to me.
My BBC is about 40psi driving back to the pits after a run on a hot day with oil temp at 200*, its 70psi going down the track so I don't worry about it

First step would be to try another gauge. Doesn't sound like a problem. Temperature from heat soak might be all it is.

looks normal to me also. A different viscosity may give a change you might like, not sure, but doesn't seem Bad. Another gauge is not a bad idea

Perfectly normal, and in perfect range.
I use idle pressure to gauge when the oil is fully warmed up.
20 p.s.i. at 1100 rpm, fully warm, using 10w30.

Totally normal. Pressure is a measurement of resistance to flow. After driving it around the oil gets nice and hot so it flows easier thereby creating less pressure.

My race engines with 20/50 start up at 75-80 psi and are 45-50 coming back from a run with hot oil.

Seems very normal for a SBC to me.
Stock / Standard volume oil pump?
What viscosity oil are you using?
Has the pressure always been about the same with the same oil?
Obviously a different oil viscosity will change the pressure, as will temperature, and bearing clearances, etc. I have seen different brands of oil vary the pressure slightly, (Quaker State 10W30 shows 1-2 PSI lower than Valvoline 10W30), and some full synthetics seem to be slightly "thinner" / lower pressure for the same viscosity.
The old rule of thumb for street engines is 7 PSI per 1,000 RPM, and for race engines, many use 10 PSI/1K RPM. I think you are good.

Stock oil pump 10W30

Thanks you all for making me feel better. It seems like sometimes I just look for things to worry about.

Thank you for the responses.

Try changing the oil filter / brand . Clean the bypass if it has one .

This message has been edited. Last edited by: BP758,

With 10W30 once the oil gets up to temp that would seem pretty normal to me.

You could bump the weight up to help it. And like 758 said above, I have noticed oil pressure differences in the past by switching filters. Smaller micron rated street filters are more restrictive. I ran into this using stock filters on my engine at break in. One time I think it was almost 15 PSI! I was nervous because I have always had the same pressures on my engine. When I switched to the racing filter the pressure came right beack.

quote:

the oil pressure falls to 25psi at an idle.

25# at idle is more than enough. If memory serves me correctly, the early (as in 1960) stock small block Chevy oil pressure warning light was set at around 6 pounds. 40-45# at cruising speed is perfect. Where folks get into trouble is using a high volume oil pump with a stock pan. It will deplete the oil in the pan uncover the pick up and pump air, that's never a good thing.

Vehicle speed isn't the indicator of the oil pressure, RPM is the ticket. 10# per 1000 RPM is your the target. Oil pumps take HP to drive.

This message has been edited. Last edited by: RPROGAS,

My Panel does exactly same thing. Cold 7o psi after some driving at idle dow around 30 to 35 psi. I do know my mearing clearance is on high side and contribute it moistly to that. Hell my 2016 2500 idles around 35 so figure hell its good.

Would not be overly concerned unless drops more over time

Street driven SBC's are notorious for low oil pressure at idle once warmed up. It's a non-issue.