No need to say “without prejudice” when you state your position openly for the record, as if for the eyes of the judge

“without prejudice” is for when you try to resolve a dispute with an pragmatic offer to which you would not want to be held in open court- so not for the eyes of the judge

The refinement “without prejudice save as to costs”- so that after a court ruling you may still show your letter to a judge to prove you were trying to save legal costs by making an early offer, and so ask for judge’s favour on legal costs