I had the same issue with my 2016 but i have 6000 on it dont seam to make a difference just has that growl in the lower end and starting to sound more like a dieselSo just bought a ecodiesel got 2000 miles on it. It is getting loader and starting to hear a growl in bottom or a rough
Fuel has improved to the point that todays additives just masked problems, There are new fuels on the market today that were NOT available when this study took place (2007) IMO todays commercially refined Biodiesel is still the BEST fuel for HPCR (High Pressure Common Rail) Diesels for lubricity.
Biodiesel regulations and the additive package to support Bio fuels,and the open market to sell Bio products.
Tractor pullers are running Bio-Diesel 100% for the additional HP and lubricity. The tractor Puller blend is nasty if it gets on paint or polish surfaces it dulls the finish.