I have a 1973 chevy 350 with about 30k miles on it. It is pretty stock except for some mild heads, intake, rv cam, and carb. When the engine was new, cold start oil pressure was 65 psi. When warm sitting in gear it would show 14psi. Now, after 30k miles, on a cold start oil pressure still shows 60-65 psi. When warm and sitting in gear it shows 10 psi. I have been noticing it slowly dropping. A month ago it was at 12 psi and now it is at 10 psi. At 60 mph it used to show 50psi and now it shows 47psi. What do you think is going on? I changed the oil, no difference. Oil is clean. I use 10w30 all the time. Is my oil pump going out or am I starting to get excessive clearance problems? Any help is appreciated. Also, I hooked up a different gauge and got the same results. So I know the gauge is not the problem. Thanks!