Surprisingly WD40 is a no-no, this will clean away existing grease and be good for a while. But long term will damage the lock. A silicone based spray will provide the long germ protection your door needs.

Surprisingly WD40 is a no-no, this will clean away existing grease and be good for a while. But long term will damage the lock. A silicone based spray will provide the long germ protection your door needs.
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