There is no performance increase using M-1 as such but the benefits outweigh all the cons if there are any, you get less friction which leads to better mileage, smoother shifting, less noise and best of all, if M-1 is used when the vehicle is new or with a re-conditioned tranny or diff, the life nearly quadruples if the oil is changed and topped up regularly. On off road conditions, M-1 is a life saver in situations where the tranny is taking massive blows and plenty of wheel spin is induced.