Giving 5 out of 5 because what plumbers in my area gave up in doing. It did just in matters of minutes. My bathroom fitting's wtaer filter was clogged and wasn't opening. Our plumbers failed to open it with their heavy pipe wrench. And WD-40 did it in just few minutes without getting any help from any plumber.
Does the job after spraying several times and waiting for quite sometime to take effect. If the screw or nut and bolt or for that matter door hinges it does pretty quick if they are just tight and not rusted. Overall OKAY. The price could be lower.
Have used better brands at same price. Spray finished quickly..bottle is half empty after a few hinge sprays. Needs repeated spraying to work well. The nozzle tube is flimsy and bends after one use. I expected better as it is a popular product.