I have a herd 5.5 spreader that I bought of CL it's been painted JD green to match my 2320 of course. I have no manuals and haven't been able to find much information about it online. My question is, it has a small weeping leak around the PTO seal and I periodically need to add gear oil (this is what I was told as I have not used it yet) how much gear oil is needed? Do I remove the fill screw and fill until that point? The fill screw is on the front of the gear box only about half way up it. What weight gear oil is best? Should I use a heavier weight to minimize the leaking? Thanks for your help!