I'm Neal and I am here to assist you. Only accept when you are happy with my assistance. If I can't help I will open your Question to other experts.
The minimum oil pressure at 1800 rpm should be 40 to 60 psi and at low idle should be around 10 psi.
This question will remain open and I will continue to work with you even after you accept. The question will remain active for 7 days after our last communication.