Silcone changes its viscosity slightly with temperature changes as well it thins out while it is wearing out. As for weight not sure because it is a grease not a thick liquid.

Synthetic grease maintains its viscosity during it entire life and don't need frequent changes like oil.

Once you switch to this grease, just re-tune your suspension.

SuperLube is readily available in large tubes. All hardware stores and some Walmart carries it. A large tube sells for $11.