the guy at ford said to use mercon V transmission fluid. From what i saw xt-m5 is a 75w90. Are you sure this is what it takes? It didnt sound like the guy at ford, knew what he was talking about becuase he was very hesitant and asked someone else and they did that " I think .....".
G5M trans in a ZX2.
I am VERY familiar with those cars - a true expert.
ATF is recommended. But gear oil is also recommended in older shop manuals. Don't use ATF since there are so many better alternatives.
Use a dedicated modern gear oil. Dino Pennzoil Syncromesh works great. So does Red Line MTL or MTL/MT 90 mixed 50/50. I have Amsoil MTF [Synchromesh synthetic] in mine now. It is very nice.
Great shifting, and much better wear protection than ATF.
Get a 6 point 23mm socket. The drain and fill holes are the same size.
Use the forward facing fill hole to fill, NOT the VSS hole use a funnel and an extension from under the hood for filling [level ground].
3 to 3.5 qts will be needed, depending.