Folks-- Need final opinion since Redline products seem to be hard to find around here. I hear good things about Redline NS but also about Mobil 1 LS---The difference between NS and LS does concern me as I want a no hassle gear oil change in my ZF with not having to add any additives. Redline 75w-90 NS or Mobil 1 LS? 4 Qts? Thanks