An 08 with 14k sounds like a lot of short trips. I would put a large bottle of injector cleaner and then drive it like I stole it for about 20 mins.

 

do you really have "a winter blend" in States?

i know that in diesel fuel there needs to be more non-freezing fuel available winter time, so called winter quality diesel, or the fuel filters will not filter it and in worst case tanks freeze...been there done that with one diesel-powered mercedes. thats the reason i prefer gasoline powered vehicles.

 

Yes !! In most instances it is a blend to minimize vehicle emissions that pollute the air. The States and/or areas that have this requirement, have specific dates the blends are in use. It is based on when the air pollution is the highest, do to weather conditions, vehicular traffic, etc.