People are always asking the Heartland Lock locksmith what they should use to lubricate locks.
Our Locksmith says: Especially in the keyway, I prefer a Teflon lubricant such as the Master Lock Lubricant (3 different sizes) that we sell under our “Locksmith Services, Keys, Parts” section. These products, if used sparingly, don’t get on the keys and stain your clothing.
I am also a big fan of good ole 3-in-One oil, especially for shackles and other moving parts. a drop or two of oil once or twice a year in key places will extend the life of your locks, prevent freezing and make them work like new.
While WD-40 is a great product, I do not recommend it because the very low viscosity of the lubricant penetrates well, but does not provide adequate of long-lasting lubrication.