50 hour service is a hot topic here.
Years ago, 50 hour service included changing fluid for most/all Kubota tractors, but it doesn't anymore.
I changed my fluid, and many also have. Others consider it a waste of fluid and $$. I considered the most important fluid change....
I'm probably in the minority with changing fluid, but as imnukensc said....it's cheap insurance.
I spent $15,000 for a tractor; am I going to quibble over $80 for a first change? Some BX guys have had the HST plugged with RTV-like sealant, and others have found some serious metal filings - - both originating from the factory. Didn't have issues later, but good to get them out of there.....