Just becuase the fluid meets misc specs does not mean it is ZF approved for that trans.... It isnt

This is one of those Ven diagrams problems that people get wrong...

ZF6 is the only fluid recommended or spec'd by ZF for this transmission

ZF6 is complies with Shell M-1375.4

Febi whatever fluid also meets Shell M-1375.4

This does not mean that Febi is approved for the ZF transmission



I will also opine that could use almost anything and wont notice anything for months or years...or never.

Does saving a few bucks every 50k really matter??? Even doing a 2x drain and fill its only 100-150 you save.