The worst selloff in crude oil since the financial crisis is turning into a bullish sign for Argentina’s bond investors. Whilst oil-exporting nations such as Venezuela have been battered as the U.S. benchmark price tumbled to a five-year low last week, the decline may help cut Argentina’s record fuel import costs by as much as 20 percent in 2015, according to former energy minister Daniel Montamat, who now runs consulting company Montamat & Asociados. The savings would bolster foreign currency reserves…