The 350 in my Camaro has about 220,000+ miles on it. I bought the engine with that many miles, since its all I could find at the time and I needed a way to and from work. I change the oil every 3000 miles. So, what is causing it to have such low oil pressure? If the engine's cold and you start it up, it'll go right up to 40-55, but once its warmed up, it hovers on 30 and if you go further than around the corner, it'll go down to almost 15 (especially when @ idle). I just wanna know if its getting ready to throw a rod or just die or what? Please give me your advice. Its greatly appreciated.

Those numbers are lower than usual, but not catastrophic or anything. In fact, they are about the norm for an engine with a standard pressure oil pump in it, such as would be the case if someone had replaced the pump and put in a regular M55. IOW, they're entirely adequate, even if a bit low.

People will give you the "10 lbs / 1000 RPM" rule, which is fine for determining if you have enough for racing, but is a different question from what's "normal".

But I'm guessing this all is with just the stock gauge? In that case, those are known to be inaccurate and to fail frequently. The part of the system that goes bad is the sending unit. Just change that out: it's cheeep and eeezy. See if that makes the gauge read higher, and consequently, helps you feel a bit fuzzier about your motor.

Just an FYI, My oil pressure is the same as yours, even after a complete rebuild of the engine, everyone said it would be fine, has always made me nervous when it gets down to 10-15psi at idle. I can't tell you if the oil pressure is the cause but 20k miles later I have a knocking 383 engine. You may want to put a high pressure pump into her just in case.

Oh, and I have replaced the sending unit multiple times, I'm still using the stock gauge and have no reason to believe that it's lying to me.

How about maybe 5w-30 oil being too thin?

5w-30 isn't too thin.

haven't used 5w-30 in any vehicle ever...I use 20w-50 in this one.

That's a good way to send a motor to the graveyard.

That stuff is like candle wax. It's MUCH too thick for the pump to pump around in there, too thick to flow properly through the filter, too thick to flow through the bearings like it's supposed to. Very much the wrong thing for our cars. I'm not sure how the idea of using that stuff ever got started; but there's no benefit. Might be OK for air-cooled (or, would that be, un-cooled? ) engines; wrong for ours.

Use 10W-30.

I have 2 cars with over 300,000 miles on them, and 3 with high 200,000s. 10W-30 in all of them. Works fine. 5W-30 would be fine too.

20w-50 thats Harley oil.

Hmmmm.. My pressure hovers around 55

Right:

There is nothing wrong with your oil pressure. The service manual specs out 10 PSI minumum at idle and 30-55 PSI at 2500 RPM. The pressure relief spring in stock oil pumps start to open around 40PSI.

20W50 is WAY too thick for any stock engine produced since the 1970's. Production bearing tolerances are too tight to be using thick goop like that. 20W50 is for race engines with big bearing clearances or a band-aid for engines with poor oil change routine and worn out bearings.