You can oil either way. I had spray bars in my Indy covers and they were fine. I also oiled up through the pushrods and that worked fine. If you oil through the pushrod you must use a block with a tall lifter boss (Mega Block). On a stock block the Comp lifters will go past the top of the lifter boss and not keep oil pressure. I also got Smith Brothers pushrods with a small hole (restricted) to keep the amount of oil down in the top end.