Have a 2012 6.7 F350. turbo went out had fixed. next day computer said had an injection problem. went to the dealer they said the DEF system was crystalized and the injectors were clogged. told me the DEF complete system would have to be replaced and the injectors cleaned or replaced. ask what DEF i used, told them PEAK. they then said I should have been using Ford DEF and i would not have had this problem. Anyone out there had this problem or know anything about such a problem.