I don't have any experience with lock de-icers, freezing temps being a VERY rare occurrence here. Ditto the previous suggestion of dunking locks in Anti-Freeze.

Basically you want a light lubricating oil that contains GRAPHITE, or molybdenum (aka 'Moly') - BE SURE to use Plastic or Rubber GLOVES, as the BLACK STAIN is very difficult to get off your hands and pretty much IMPOSSIBLE to get out of clothing.
2 of 3 Bike Lock makers websites (ABUS, KRYPTONITE, and ON GUARD) RECOMMEND a light Graphite LOCK OIL to maintain their products. One website (can't remember if it was Krypto or O. G.) recommended a Teflon based oil /"Tri - Flow" ?? IIRC. The "Moly" lube was recommended by a Residential/Commercial lock maker (Schlage, I believe).

Use WD-40. *ONLY TO FLUSH OUT*, water, old lubricants, and SALT (assuming they Salt the Roads and walkways up in the Great White North, eh?). USE FRESH LOCK OIL in the keyway, a light coating of the locking bolts AND their guide tracks, PLUS, a heavier coat on the exposed metal ends of the U-shackle, PAYING PARTICULAR attention to the surfaces of detents that the locking bolts engage with.