Hi all, new to the forum so pardon me if this a a dumb question. Im thinking about changing the diff oils in my 07 1500. 47000 miles on it since new and i don't think its ever been changed. I have read like 15 different recommendations of what to use and whether or not to use an anti-slip additive. What is the official thing I should do (what brand, type, and how much)? Also, can I expect a small MPG increase?