The recommended decision is that you should not use WD40 for your hedge trimmer blades,
although WD40 is the multipurpose lubricant of all-time favorite for a variety of machines and shows the effective results.
WD40 is a penetrating oil or spray which aims to protect metals from rust and deliver lubrication as well.
It is well used on hinges, wheels, pulleys, rollers, chains, and gears.
To lubricate blades of hedge trimmer 3-IN-ONE Multi-Purpose Oil is the best choice.