Is there anyone here who is an autmatic transmission specialist advise which fluid I should use for a ATF change on a 2.5 Legacy 2004 Model (4speed auto/tiptronic)

I was going to have the fluid/filter chanegd next time my local garage service the car - I was advised by the main dealer I bought he vehcile from that regular fluid changes were advised to keep the box/awd system working.

The handbook suggests Idemitsu HP, Subaru HP (the same thing rebottled ??) Catrol Transmax J, and some american Pennsoil stuff...

None of these seem available for sale in the UK (unless anyoneknows otherewise)

The handbook does mention 4speed autos can also use Dexron III, but looking at several forums some people suggest it can give hard shifts and the synthetic HP stuff is what is preferable in vehicles from 04 onwards... (and essential in the 5speeder..)

Is there an aftermarket synthetic fluid that is known to work OK in these gearboxes and not cause damage/hard-shifts premature wear etc.

Threre are several aftermarket fluids that claim to meet the Subaru HP spec, but they also claim to meet virtually every other imagineable ATF fluid spec, so as a scientist I am sceptical they can actually do this as surely the specs mustbe quite different....

or do I have to buy the Subaru HP stuff from the main-dealer and get sh##ted in the wallet...