Prova has a slick method of returning oil to where it should be. Blow by is collected and passed back to the oil pan via the oil fill neck.

In comparison with normal style oil catch tanks; blown by gas can be pulled out from this model's oil filler cap. Operational loss of the pistons and pressure inside the crankcase are decreased due to discharges of the blown by gases. In addition, oil return to the suction pipe is collected through the catch tank.

Removal of the oil filler cap can be done without the removal of the hose and nipple.