Last year end of race season my cars oil pressure would go down when under power and when I let off the throttle it would come back up. Engine has been completely rebuilt and new to me oil pump. It took a bit to prime and get pressure. Then car was fine. We ran it 10 to 15 mins and then a few days later we ran it again. Hasn't started in 3 weeks and now no oil pressure again.... Can anyone give me a reason why? Also I used lucus break in oil. Please help ! I have open practice this weekend.