The misconception lock lubricant and WD-40

1. How Locks Work and Why Lubrication Matters

Locks have many small, precisely machined moving parts — pins, springs, tumblers, wafers — that interact inside a tight space.

• These parts need low-friction movement to function smoothly.

• Dirt, dust, or sticky residue can cause pins to bind, making the lock jam or wear prematurely.

  
  

Lubrication in locks serves two purposes:

1. Reduce friction between the metal parts.

2. Protect against corrosion without attracting dust or creating gunk.

Because locks have such fine tolerances, they require lubricants that:

• Stay slippery for a long time.

• Don’t gum up over time.

• Resist attracting dust and grit.

  
  

2. Why WD-40 is Not Ideal

WD-40 was originally designed as a Water Displacement formula (hence "WD").It’s primarily a penetrating oil and solvent, not a long-lasting lubricant.

Problems it causes in locks:

1. Residue Build-up

   • WD-40 leaves behind a sticky film as it evaporates.

   • Over time, this residue traps dust and dirt, creating a sludge that can make the lock harder to turn.

2. Short-Term Fix, Long-Term Problem

   • It will make a stiff lock work better temporarily because it dissolves dirt and frees stuck parts.

   • But as the residue builds up, the lock can get worse than before.

3. Thickening Over Time

   • The residue oxidizes, turning into a gummy varnish that can actually glue pins together.

4. Cold Weather Issues

   • WD-40 isn’t designed for extreme cold. The residue can stiffen or even freeze in sub-zero conditions.

     
     

3. The Right Types of Lubricant for Locks

Locksmiths generally recommend dry or non-gumming lubricants, especially:

• Graphite Powder

  • Dry, non-sticky, perfect for pin tumblers.

  • Doesn’t attract dust or gum up.

  • Works well in cold weather.

  • Downsides: messy, can stain, and not great for locks exposed to rain (graphite + moisture = paste).

• Teflon/PTFE Spray (e.g., Tri-Flow, DuPont Teflon)

  • Goes on wet, then leaves a dry, slick coating.

  • Good for both indoor and outdoor locks.

  • Resists dirt better than oils.

• Silicone Spray (Dry Film Type)

  • Good water repellence, stays slick without getting gummy.

  • Works well in weather-exposed locks.

Avoid:

• Heavy oils (e.g., motor oil) → too viscous, traps dirt.

• Grease → even worse for attracting grit.

• WD-40 as a routine lubricant → fine as a one-time cleaner, but always flush and re-lubricate afterward.

4. Summary Table

Lubricant Type	Pros	Cons	Best Use
Graphite Powder	Dry, no gumming, great in cold	Messy, not for wet climates	Indoor locks, cold climates
PTFE/Teflon Spray	Low friction, light coat, dirt-resistant	Slightly more $$	Indoor/outdoor locks
Silicone Dry Film	Water resistant, clean	Slightly less long-lasting than PTFE	Outdoor/weathered locks
WD-40	Good cleaner & rust remover	Leaves residue, attracts dirt, gums up	Emergency freeing stuck locks