Contaminated Coolant in Astra?

My brother inlaw has a 2007 Astra 1.8 automatic. the ecotech engine. Temp light comes on. I checked it over and did basic tests, on the last test I took of the two top hoses to the expansion chamber and run the engine. No fluid appeared, I then give it a quick rev and we had something out of both hoses. What came out was a small amount of coffee coloured goo the texture of warm syrup. I have read on internet that the contamination could be in the gearbox area. And the engine oil is normal looking and at a constant level with no gunge at the rocker cover area. any ideas would be welcome