I did my ZT HD 52 hydros yesterday. Other than the 1,000 degree temperature, 3000% humidity, and no air movement in the garage, it was no trouble to do. The top plug comes out with an 11/16". The filters are small enough that standard size Channel Locks will grip them enough to remove them. Evidently the same 500 lb gorilla that installed my F150 filter at the factory also installed the hydro filters. I have a filter wrench made for a 3/8" ratchet that's made of plastic. It slipped when taking the filters off so I went to the Channel Locks. It was more than strong enough to tighten the new filters to spec. I used Mobil 1 15w-50 synthetic to fill it. Purging was a breeze, and I was back out mowing in the bright sunshine (but cooler than the dang garage) in no time.
BTW, if you lift the mower with a block and tackle or come-along, you can safely tip it a little to the left or right and get more oil out than if it stays perfectly level.
BTW, if you lift the mower with a block and tackle or come-along, you can safely tip it a little to the left or right and get more oil out than if it stays perfectly level.