Send me your email address and I will send you the complete manual of passo 2008 by email.
Its confirmed ATF and recommended gear oil is T-IV.
Go and smack that mechanic who told you to do so.
Drain the previous oil and don’t drain it in dirty container. Drain it in neat & clean container, and re-pack it. You can give to some other PW member who need this. Because its useless for you but someone else can use it.
Friction level of CVT & ATF are entirely different. If you will keep running it, after 1 year or so, the total automatic gear will be done and you have to buy the new one which is just ~Rs. 600,000/-. Yes the automatic gear of passo is more than 5 lack.
So you better take decision now rather to repent later.