Gunge in rad water bottle

Hey guys,

Topped my STI up with oil and coolant yesterday. i noticed in the water bottle that there was a black gunge around the sides of the bottle..

Is there oil getting into the water..?? Head gasket maybe..?

Plus she takes a drop of oil ( dip stick goes down about 7 mm ) every 4 weeks is this normal for impreza's..??

Thanks

dont think its head gasket... what year sti is it

when you say a gunge around the sides of the bottle do you mean you cant see through the bottle...id say its the just when the coolant heats it discolors the side of the bottle....happened in almost every car i have had

take the oil filler cap and check for a mayonaise type gunge in the cap...that would be a sign that the oil is mixing with the water......

There seems to be a black moss like fungus around the inside of the bottle. the water looks clear tho and i can't see traces of water in the oil..??

Car is a 98 STI and is running perfect .. just concerned incase this could lead to a bigger issue.

Maybe clean out the bottle and do a coolant change ? Wont do any harm anyway

As above,

Its no problem. Could be someone used water at some stage. I'd just clean out the bottle and fill it with nice clean coolant.