I think it helps to have the whole front of the car lifted as well to help the coolant flow down the coolant pipes along the sides of the car. I left both caps off while filling until the rear level hit the degas tank. Capped the rear, then continued topping off the front in its raised position, capped the front, lowered the front, topped the rear. I felt leaving both open during the initial part of the fill would allow trapped air an easy way out, especially in those low areas along the sides. Seemed to work.