[carlh]

Hi, sorry forgot to follow up ... But yes, it seemed to be just a dilution thing. Trickle at first, one headlamp washer only, then all began working. It has now been ok (touch wood) so must have been weak dilution. I've been using 75% strength. I agree from my limited experience that long journeys do not warm it up it seems - so dilution must be the major factor.