I have plenty of the original GM #1052367 OES assembly oil/oil additive in the black bottles available.
Discontinued by the General a few years ago in this formulation, it has been reissued in a new "friendlier" version since using a white bottle and the same part #. It is NOT the same. Its supplied in a 16 oz bottle, suggested use is a full bottle for break ins and 1/2 bottle added to every oil change. This product has plenty of Zinc in it to protect all our expensive flat tappet camshafts and pistons from scuffing and is what GM recommended using since the early 60's! Back then it was supplied in a tall cardboard type of can with metal top and bottom and was called engine oil additive, not assembly lube. Yes it was exactly the same, same part #, the instructions read "suggested use one can at every oil change. They probably were on to something! I still have some of those cans!
Buy the bottle its $25 plus S&H, by the case of 6, $135.00 plus S&H
Get it while my supplies last!