Heartland, My owner's manual for my 2008 Bighorn 09162 just notes a "6 month" time interval check for the wheel bearings. Since I am an advocate for "preventive" maintenance, I would like to know if there is a mileage criteria for greasing the bearings or if it is just based on a calendar time? What is the recommended grease, Lithium, marine, or any standard wheel bearing grease? Thanks for the response. Rich Keida, Willow, Alaska