Under the seat.
John deere hy-gard or any good trans. Hydraulic oil
The 2305 john deere was a new model starting in 2005 It would be sold with the front bucket it is a 23hp yanmar engine 4wd and a 18hp pto
John Deere 2305 and 2320 Compact Utility Tractors are assembled at John Deere's Augusta, Georgia (USA) factory.
back of tractor below fuel tank.
Go to your John Deere dealer and pay big bucks for their hydrostatic fluid or go almost anywhere else and buy a good quality hydraulic fluid.
Where is the hydraulic fluid drain plug on a John Deere 7410 Tractor
if you are referring to the sight glass when the tractor is running the fluid will not be seen in the glass because it will be in all the hydraulic lines and pumps
low viscosity Hy-Gard Transmission and Hydraulic Oil
I the cab. The transmission fill also supplies all of the hydraulics.
any hydraulic transmission oil such as Hy-tran Case IH or Hy-Gard John Deere
A 2155 w/o 4wd holds 50 qts of hydraulic fluid. A 4wd takes 53.2 qts.
Manuals are down-loadable (as PDF) from the site to which I will make a link for you below.