Does anyone remember the graphite oil Arco used to sell?   Was it any good?   A friend of mine has given me a case of it.  It's old enough that you need the old stabber spout to open it.   Would adding a quart of it to my regular oil be detrimental?   My truck block has a 6 quart pan.   So when I change oil I can use 5quarts and add 1 quart of the graphite oil.