I did a complete fill of M1 75w90 (7 quarts) in the Dana 80 in my Dodge. Even though the bottles said that it was for limited-slip differentials, the rear end would chatter in tight slow-speed turns. So I bought the LS additive separately; 2 4-oz bottles and problem solved. On other fills I have used Walmart Supertech, and didn't have a problem with limited-slip chatter. So I avoid M1 gear oil.