Do I Put WD-40 on a Car Lock Before It Freezes or After It Freezes?

by Chris Gilliland
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As winter begins to settle in, motorists are presented with several issues that are unique to the season. In colder climates, standing water can become a problem, not only on the road, but also on your car's door locks, freezing them solidly in place. As a remedy, many DIYers use common household product WD-40 to prevent their door locks from freezing. However, WD-40 must be applied carefully and cleaned off in the spring to prevent trouble down the road.

Understanding WD-40

WD-40, or Water Displacement - 40th attempt, is a multipurpose lubricant spray that has a range of applications well-suited to any home or garage. While WD-40's exact formula has never been revealed, it does contain petroleum distillates and highly refined mineral spirits that provide excellent cleaning and lubricating properties. However, WD-40's formula was intended to displace water, effectively preventing water from pooling or standing on a well-coated surface. This property is what prevents car door locks from freezing in colder climates.

Frozen Door Locks

Car door locks require a small amount of moisture, in addition to temperatures below 32° F, in order to completely freeze. Unfortunately, moisture is ever present in the winter months, since rain, snow and puddles are common throughout the season. The requisite moisture can build up on the lock's metal surface before seeping into the door lock mechanism. As temperatures drop, the moisture freezes and prevents the lock mechanism from moving, effectively leaving a hapless motorist out in the cold. An unprotected, frozen door lock is best approached with a de-icing spray or a warmed key.

WD-40 and Freezing

The water displacing properties of WD-40 can be used as a preventative step in winterizing your car or truck. Spraying a small amount of WD-40 into the lock mechanism before an expected freeze will coat the metal components to deter moisture from gathering or pooling. Removing the door lock entirely during WD-40 application can ensure complete coverage of the mechanism, providing the highest degree of protection.

Problems Associated with WD-40

Although WD-40 has many benefits and can prevent car door locks from freezing, its petroleum-based formula can cause problems. By nature, WD-40 is somewhat tacky and can trap road grime, dirt and debris. This could lead to a sticking or difficult-to-turn door lock. If the condition is allowed to worsen, it could prevent the lock from opening entirely. If you do plan on using WD-40 on your car's locks, the locks should be removed and cleaned as soon as warmer weather can be expected. As an alternative, there are several lock-specific de-icing products available at most auto parts stores, many of which can be used without harmful effects or time-consuming cleaning requirements.

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