Should I be worried about this white stuff in my oil filler cap, Always got told it was bad but cars been fine.

Changed oil oil filter plugs and cleaned k&n today oil was very black was changed 6 months ago only did about 4k not using oil or water either

Might just be condensation...it's a very small amount. If it was a HG failure, I'd expect to see a lot more more "mayo" than that (of course, it is also possible for the HG to fail and NOT do that - like my old Punto...which was just like "Hey, Imma bored - Imma gonna poppa de head gasket!!" apologies to anyone of Italian heritage for my poor written accent lol)

You also say the car is running fine - which again suggests to me condensation.

If in doubt, could always run a compression test - that should identify a failed HG.

that amount quite normal especially on short journeys when engine doesnt get warm enough,

Yeah that's nothing to worry about, as ian says it will most likely be condensation if you do quite a few short journeys.

Fair enough thought maybe the start of somethin bad...I know what you mean about puntos worst car I ever owned lol thanks all

had 2 mk1 puntos not an issue from either sold one at 87k other as written off after it was hit that done 4 yrs however my mates had 2 head gaskets that looks like condensation head gasket is thicker than that

Your focus is certainly no punto!!!!

Honestly head gasket issues aren't common on the focus if it was a rover IDE be stripping the head off lol I assume the dip stick I fine also a look in the oil cap hole with a torch would show if there's any foam in there if not condensation