Hi I am new here I have been looking around quite a bit but still don't understand a lot of what I am looking at in oils & gear oils? I have a 2003 Dodge 3500 dually 4x4 with the cummins diesel.I have around 33,000 miles on it & want to change the front & rear differential oil. It calls for a 75w-140 synthetic the 2 I am considering are Mobil 1 & Amsoil severe gear. What I whant to know is one better then the other or is there anything out there any better then these two? Also if this makes a difference I do a lot of towing a 11,000 pound boat.
Thanks Charlie