Gearbox oil 5speed zf

[mauro12]

Hi guys , I have the 5speed zf gearbox , I wanted to ask you how often should the atf oil be replaced in this gearbox .
I know that should be replaced every 60.000km or so but I will never do this mileage in the near future . Is about every 5 years maybe ? 
Ps: is it true that the 5speed has an harder 1-2 gear shifting that the 4speed  ?
Thank you