"dont want to break whats not already broken"

Unfortunately, it probably already is broken, but that "grey" ATF is masking the failure.

This and other boards are repleat with examples of people changing their ATF for the first time at a very high mileage and then having their transmission fail soon thereafter.

The consensous of a number of automatic transmission engineers who I have contacted about this very question is that if the transmission fails with the ATF change, then the friction surfaces were already glazed and the new (read slippery) ATF upsets the preexisting balance between friction and lubrication.

The fact is that the changing of the fluid does not cause the failure--the failure already exists--it simply reveals the failure.

Bottom line, whatever you do, it's a craps-shoot.