Hi..Engine oil is a much discussed subject in this forum,I've seen Rotella T6 petroleum oil,no mention of Rotella T5 synthetic blend oil,I just purchased some for my b6100 912hrs, its of CJ-4 rated , 10w-30, easy to find Wal-Mart,I live in New England, will be plowing snow, avg.night temp. 10 degrees F, any comments? Other questions, OK to use chains on all 4 wheels plowing? b6100d, can I lock the differential while plowing snow ?