Could you be more specific on the location? The hydraulic oil does not get pumped through the engine. Does it leak more with the engine running or engine off? Are you leaking from the HST (transmission)?
For ref. you sit on the HST. The engine drive shaft (always spins while it is running) goes into the HST and drives your main hydraulic pump.
If the leak is coming from the block, dripping off it, its probably engine oil or a leaky hydraulic line.
BE VERY CAREFUL looking while it is running becuase a hydraulic high pressure leak can inject you with oil. It isn't pretty how the clean you up at the ER. Your manual shows how to inspect the lines for leaks.