Retractable hardtop maintenance:
2 salmon relays every 5 years to avoid destroyed hydraulic pumps. The manufacturing date is printed on it as YYWW.
2x rear ventilations behind the bumper: all 2009 and 2010 Z4
2
gas pressurised props on the main columns to support the hydraulic pump and get a smoother landing of the roof package
2
microswitches on the left and right kinematic boxes every 8-10 year to avoid unexpected stops of the CTM
1 roof harness after 8-12 years to replace broken wires and hydraulic hoses
1 oil change on the hydraulic pump after 8-10 year, you need 1l of (i.e. Febi or Mercedes) ZH-M hydraulic oil