brown sludge in engine?

hi sorry if this post is in the wrong area I cudnt find where to put it,anyway heres my problem.



I have a rover 45 2003



I took the wee lad to school this morn and noticed that the heating wasn't working in car so got home and had a look under the bonnet the water tank was empty so I filled it and steam was flying out of it after a few fills it died down and heating was working,so I checked the oil and its brown.



is this the start of the head going?



at the minute the cars going fine ie heater working,driving well







again im sorry if this post is in the wrong place





any help would be very appreciated

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