Vincent,

The AP grease kit is not on their website, you have to call them for it, but I would think you could also get it from their European distributor.  The kit includes good instructions.  You will also need the "gear mesh" instructions available on the AP website.

The kit includes two kinds of grease, one for the worm and worm gear, and another for all the spur gears.  If you want to use commercially available grease AP could advise you.

Steve