I recently purchased a 2005 S50 in perfect shape with 10,000 miles on it. I saw a very small drop of oil under it which is coming from the bottom of the rear air box drain hose. The end of the hose has a rubber or vinyl cap on it very firmly attached to the rubber hose, seems either glued or vulcanized to the hose. It may just be stuck, but I do not want to try and rip this off if it´s not supposed to come off. Does anyone know how to drain this hose? It´s not in any manual. I haven´t seen the front air box drain hose, can´t find it without taking everything apart.