I have a Honda HRC216 with Hydrostatic drive. If you take the bag off, lift up the flap on the rear of the mower, you should see the Hydro drive with a dip stick on the top. You can check the fluid with that dip stick. You can buy the Hydro fluid from a Honda dealer for about $12 a quart. I actually changed my fluid because it was very dirty. Drain all the gas and oil out of the mower and turn it upside down to drain the fluid out.