Just bought my son a 2006 KTM 65 sx. There is oil in the coolant. I took off the coolant pump cover and removed the propeller. Behind that is a seal. I was hoping that is where the problem is coming from but I can't tell if anything is wrong with the seal. If it's not that seal then what? I only have a slight amount of moisture in the oil that looks milky, but the radiator has sludge all in it.