The spot cash differential for 380-cst high sulphur fuel oil (HSFO) slipped into discounts on Friday, as ample supplies continued to weigh on the market. The 380-cst HSFO differential (FO380-SIN-DIF) fell to a discount of 30 cents to Singapore quotes, after staying in premiums for at least a month, while the 180-cst HSFO differential (FO180-SIN-DIF) …