I bought a 2004 Yukon 4x4 about 6 months ago. I'm changing the transfer case fluid today and got Valvoline synthetic transfer case fluid (says it's Auto Trak II compatible) since I have NP8 in my build sheet. I dropped the old fluid and it looks like not-too-dirty engine oil or gear oil. I expected it to be red since the new fluid is red. Should I be worried? Did the PO put the wrong fluid in there? My 4WD works fine, by the way.