My SLS fluid is also very dark, however I've never flushed the system. Does dark fluid automatically indicate that that there is a seal leak allowing engine oil into the system or may I it just be dark from wear and tear. I'm not having any overflow issues or loss of engine oil as knipdlo indicated he was having. Just a saggy rear (when engine is off..I assume leaking seals in the valve).

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'85 300td Frybrid WVO Kit