wheel spinning = class
Could be sensors, valves, fluid, software... Not sure re Z but the Vovlo T5 Geartronic I have now has oil 'for life' which is absurd, changed the ATF fluid and the gearbox is much better now, didn't do a full flush yet since it can disslodge crap in the gearbox if you dont know the full story of it is so currently only done plug out and and in and replaced about 1/2 of the total ammount of fluid.
Whats the history of the car/gearbox and oil changes? As I said not sure if there is a service interval for oil change, could even be dodgy oil used in the last change, went around to some of the bigger garages looking for ATF fluid for mine and the @*!# stuff they put in the auto boxes I'm NEVER handing my in to a non trusted mech ever... anyway. What year car is it?