you know, I guess I just went with the common knowledge recommendation to use JD Polyurea, but after looking over the specs, it sure seems that the Mystic JT6 that I mistakenly used on the spindles is a far superior grease. I think you may be right that JD PU is nothing special when compared to other greases. I use JT6 on my truck and virtually everything else I use grease on. I just may switch the whole tractor over to JT6 and be done with it. I'm not saying the JD PU is inferior, as it probably does a decent job. I actually thought it would make sense that if the factory uses it, they would not be using a grease that is not compatible with the single most prevalent grease out there, which is Lithium complex. Also, I think I read a long time ago, but can't remember where, that someone did call JD tech support and asked this very question and was told mixing was fine, at least for these two types.