Hello all.
I did a coolant flush and changed it about two months ago. Yesterday, when I removed the cap to check the levl, I noticed that its bottom was covered with a kind of white soap.
Where can this come from? I suspect it can be oil from a leaking head gasket, do you agree with me? Or it is simply rubbish from the circuit?

Thanks!

190E 2.3, 190000kms, 1992