yes I will do what this comment is telling me to do'best cost' isn't necessarily BEST.
Download a copy of the owners manual and the WSM, see what they say about 'oils'. Also ask the current owner what he put in.
Google search 'l295dt fluids', you'll get several hits, some from here and read what others say
Since the BH is a self contained system, something like AW32 or UTF should work but you must be diligent about removing as much of the old oil as possible. Typically it's a 3 part process. 1st flush removes 99% of the old , 2nd flush removes the last 1% (sort off) and 99% of the 1st new oil. Then add the 'real' oil.
Best to cycle every spool valve several time, allow oil to heat up,be sure to replace filter before adding the final good oil. The reservoir could take 5 gallons ??, so $200 for the flush, $100 for the 3rd fill
I might use super cheap fluid to flush it out, then put the recommended one at the end