Adjustable camshaft having improved oil transfer between the inner shaft and outer shaft

The present invention relates to an adjustable camshaft (1) having a hollow structure the outer shaft (10) and with a in the outer shaft (10) rotatably accommodated inside shaft (11), wherein the inner shaft (11) having a cavity (12) with oil can be acted on, and wherein in the outer shaft (10) at least a first radial passage (13) and in the inner shaft (11) at least a second radial passage (14) is formed so that oil at a coverage of the first radial breakthrough (13) with can flow to the second radial opening (14) between the cavity (12) and the outside of the outer shaft (10). According to the invention it is provided that the first radial opening (13) on the inside (15) of the outer shaft (10) has a larger cross-section than on the outer side (16) of the outer shaft (10).