Hi I have a 2002 Chevy S10 with 155,000 mls with the 2.2 liter. When I start it up in the morning the oil pressure goes to about 70 lbs, then after it warms up it drop to about 30 lbs. What could cause this?
The engine oil is warming up.
Sounds about right, my 2000 Blazer’s 4.3 (117k) oil pressure is ~80 cold and ~40 psi warm. It’s been this way as long as I can remember
normal operation
This is typical behavior for an oil pressure gauge in a GM vehicle. It probably changes with engine speed as well, going up as engine speed increases. This becomes more apparent as the vehicle ages and accumulates miles due to typical wear and tear on the engine. Your oil pressure is good, so you don’t need to worry about it. If it starts dropping to 5-10 psi at idle and triggering your “check gauges” light, your engine is worn and on borrowed time. You probably have a ways to go before you have to worry about that.