By MarketsFarm WINNIPEG, March 17 (MarketsFarm) – The Canadian dollar was lower on Tuesday, finishing at its lowest level in four years as oil prices weakened. The dollar finished the day at US$0.7055 or US$1=C$1.4175, compared to Monday when it closed at US$0.7161 or US$1=C$1.3964. Benchmark crude oil prices were down on Tuesday as the