I recommend and use Stjarnagloss Mild. No dedicated lube required, save your monies, and use it with water. Awesome, and if used correctly, perfectly safe and wont cause any damage!
Although, it's cheaper to buy the quick detailer and the clay separate if you know where to look. You end up with more lube, the same amount of clay and about £7 better off.
Bilt hamber auto-clay is good and only needs water as lube! pretty sure you could get away with using water with all of them, just a money making scheme imo!