Since I got the intake back on the car, and changed out the oil I've been getting real low oil pressure. I just changed the oil again today, and a found a little coolant left in it. The current oil shows no signs of coolant being present. What does the oil pressure on one of these cars usually run at idle/normal throttle. It's a 83 z28 305 carbed motor.

 

Coolant in the oil is never a good sign. I hope you don't have an internal coolant leak. I don't know what oil pressure in an 83 305 is, but in my 91 305TPI it is just a bit over 30 PSI at idle with the engine being hot. I run 5W30 motor oil in it and the motor has just a little less than 3000 miles.

 

On my 84 305 cold idle oil pressure is around 60 and when warm it drops to 30

 

Not an internal leak, coolant level is staying constant. I guess I just got that much in the oil when I removed the intake. But even now I have very little in the oil but my pressure is running about 45 at cold idle, 15 at hot idle and around 30 while driving. Any suggestions as to what could be causing it?

 

Not to flame but it sounds like you took the lazy way out, you didn't even drain the coolant before swapping intakes, it really doesn't take that long, you spent more time(not to mention money) changing the oil three times then it would've taken you to drain the coolant.

I know coolant severely cut's the lubricity of oil even at a 50:1 ratio it could still cause engine damage such as galling bearings, which in turn would lower oil pressure.