I had also checked the KK website after ordering my tiller so I would know how much oil to add. No help there. The manual that came with the tiller has the same language as the website but has the quantities in bold at the end of each section about gear boxes.
I added the oil yesterday just before using the tiller for the first time. I added 40oz to the top gear box. Today I checked it and it's a little over half full but a long way from being totally full. If overfilling is such a problem I wonder why KK doesn't include an overflow plug like on the side gear box?
I have used the tiller for about 4 hours so far and it has performed great. I tilled up my old garden spot that hadn't been used for over 10 years and had horses running in it. After one pass I added a mountain of old manure that had been cleaned out of the barns last year and the tiller mixed it so well into the soil you can't see any of the manure on the top of the soil.
Tom you really have me wondering now, there's no way I added 40 ozs to mine, I cked the other day and its still at one of the "arms" I can see tho the hole but I haven't used it as much as you have, no rain here til the weekend and then only a maybe, I'm going to use mine next week and check it every hour or so. I'm in full agreement with you about a overflow plug on the gear box or a dipstick of some kind made into the cap, thats a idea! I'm going to use a tape measure to ck mine, at least that would give some idea of what half way is