Teasing aside I see 30 to 45 pounds depending on what the engine is doing at the moment. The oil pressure gauge MUST come up within 5 seconds of starting to fill the turbo and so on. (Given that I pretripped and checked the oil dipstick to verify that is there.)
When I am pulling upgrade in the heat, I keep a eye on the oil pressure, it will drop 10 pounds before the water radiator temp starts to climb past 195 and keep rising. Hopefully we will get to the top in good order.
Once or twice in my life time I have lost ALL meaningful oil pressure. You kill the engine right away and get in touch with the boss. And you will either have a bunch of gallons of oil coming to you or a tow truck. You do not drive a semi engine without oil in it. Ever. Unless you think you can afford a 45000 dollar engine replacement etc.