Johnathan is correct. Although there is only one fill opening, the reservoir is divided into three compartments---one for the front brakes, one for the rear brakes and one for the clutch circuit (not used on your car). The compartment for the rear brakes only gets filled after the front circuit is completely filled. Once properly filled the brakes can be bled the old fashioned way without problem. I would top up the brake fluid after no more than 10 pump and bleed actions to prevent reintroducing air into the rear circuit due to low fluid in the rear reservoir. Mark