My car, a '70 340 'Cuda has only been sitting about a week since it last ran. I'm replacing the exhaust system and I thought since the head pipes were removed it would be easier/cleaner to change the oil and oil filter now. However, my oil, which I had to "mail order", won't be here until tomorrow. Once received I can add the 5 quarts but won't be able to start it for a couple more days when the exhaust system is completed. I guess my real question is: Is there any difference, where the prime in the oil pump is concerned, whether the car is sitting for a week with oil in the oil pan or no oil in the oil pan? Would simply draining the oil from the oil pan cause the pump to lose its prime? Thanks