I would recommend greasing the poly ends with Energy Suspension 9.1110
http://www.energysuspensionparts.com/proddetail.asp?prod=9.11104 After 650 miles, I too am noticing a small amount of sqeeking over big bumps on my Duster.....I will be applying the grease over the winter. I see other products on the market, ...... a green synthetic marine grease and Super Lube 41150
Super Lube 41150 Synthetic Grease (NLGI 2), 14.1 oz Cartridge: Power Tool Lubricants: Amazon.com: Industrial & Scientific but since Energy Suspension makes the bushings, I will use their grease