If only they would break easily! However, the WD40 is just for getting them off. More often than not, the plastic nut is well and truly fixed to the stud and without some pre-treatment, turning the nut will break the stud. I would go with silicone grease before refitting, but having only removed any single nut once, I don't know how long it would last. It's a another poor method which Saab used for fixing trim etc.