It seems to me that the boots and grease on the upper, lower and steering link ball joints are purely cosmetic. The ball joints are permanently lubed from the manufacturer (probably not much lube, just a steel ball encapsulated in a nylon/delrin cup) and pretty much maintenance free. The little bit of grease retained by the boot is likely there just to protect the exposed portions of the ball from corrosion. The lower and steering link boots were damaged during disassembly (I hate pickle forks and brute force but somtimes there's no other option) so I'm replacing them all with the PU boots that came in my Energy Suspension master kit. Functional-and colorful too. I'm going to put a bit of EP grease for protection but I'm not going to get too wound up about the amount or type.