where abouts are the streaks ??

if they are on the bodywork then a good caravan wax will do the trick (Fenwicks or Mer)

If they are on the Plastic windows I have been told that brasso will polish them out - not done it myself

.....our recently-purchased camper van had some streaks from the roof, an obviously neglected area where dirt builds up, and where roof vents have mastic around them.
So I spent some time giving the whole area a good T-cut, followed by a generous coating of wax polish ; the result is a really smooth surface that dosn't hold the dirt...so far there has been a dramatic reduction of streaks. Hope this helps.

We`ve found Fenwicks to work quite, but some of the streaks are still there, albeit very faint.

thanks for all the replys i,ll tell my husband thats his department