The stock lube is a thin grease or very thick oil depending on your point of view. GM discontinued their manual steering lube several years ago and it is not available unless sitting on a shelf somewhere. I have heard of only the Penrite and Cornhead grease as a good substitute. I went with the Cornhead grease, cheap and realitively easy to find. You should not use a straight grease as it will "cavity". Which means it will get pushed away from parts as the steering box parts move and will not flow back into the ball nut area.
