I have the unusual model option of FWD on a 2012 xc70 and trying to understand what is the factory recommended transmission service OR what should be done that the Volvo manual
doesn't mention ? Should the trans oil be changed at 120, 150, or 190k miles ?

 

There is no change interval (for normal service, unless you get a message) - but Volvo suggests changing every 52.5k if used in a severe manner. Newer Volvos (2013+) changed to a 10k service interval (specifying synthetic oil in the engine) and the trans change under those conditions, changed to 50k.