I also noticed oil inside the cooler tubes and intakes, so that doesn't surprise me. The car has 92,*** on it
Might as well throw a solid coupler into the SC if you're replacing the seal and changing fluid. If it doesnt already have one.
Oil inside the lower air charge tube / intercooler is common. Engine oil gets vaporized and pulled through the intake / PCV, when it cools down in the IC, it condenses and collects in the bottom / lower tube. Considered normal in the Ford service manual, but there are many out there who have an oil seperator in the vacuum hose. I never bothered to install one.
Most of the time the SC oil comes out through the snout seal before the rotors, but the oil inside your IC is most likely engine oil.