VOLVO recomend cahnging the transmission fluid every 37k IF the car is either used for towing, used as a taxi or driven hard (thats from teh OFFICIAL volvo service system)...

I have personnaly done a change on a car with 60k miles on the fluid and im telling you it was nasty (and i really do mean nasty!) - so much so I would actually say it is worth the £70 every year/30k miles to do the change... (note over £200 for fluid from the dealer!!!!!)

Certainly for anyone with issues changing hte fluid HAS to the first step...

I used dino, but ONLY because i couldnt actually GET sythetic...

as to AT transmission failure being rare I asked my local independant specialist (who also mail order parts and is a specialist volvo breakers) and he said he has people ringing up all the time after auto boxes..not a seintific study but very interesting, anyway who would leave engine oil in for over 30k or a year and that tranny oil runs at least as hot...