WD 40 is not a lubricant, therefore while it will act as a lube for a short period (so will any liquid even water), it will not endure. It is a water displacent, hence the WD in WD 40. Use a light oil such as 10 Wt, or silicone, or white lube, or even graphite. Save the WD 40 to dry out your plugs when they get wet. I know the label says it will lubricate things and it will in estremely light duty circumstances, but it won't last and any lubricant will serve you better.