For those of you who have replaced your brake pads with stock Isuzu/ pads; what are the little packets of goop that come with the pads for? There is a packet of orange goop and a packet of black goop. I am guessing that the orange goop is to lubricate the shafts of the brake calipers so they slide back and forth easier, but I can't figure out what the black goop is for. Anyone know?