What kind of oil should be added if the key insertion and removal is not smooth?

[ElizaFitz]

For keys that are not smoothly inserted or removed, you can choose to add lock lubricating oil. Below is a brief introduction to other solutions: 1. B-type pencil: Purchase a B-type pencil, scrape the pencil lead into fine powder, and blow a small amount into the keyhole. Be sure to use a B-type pencil, and the higher the B number, the better. B indicates graphite content, and a higher number means more graphite content (such as 2B, 4B, 6B, etc. Do not choose "H" pencils, as H indicates clay content, which is very hard. If not scraped finely, it can damage the keyhole). Graphite is very soft and is suitable as a keyhole lubricant. The advantage is stable performance, no corrosion to the keyhole, and long-lasting lubrication. The disadvantage is that improper handling may stain hands and clothes black. 2. Paraffin wax: Apply paraffin wax to the key and then insert it into the keyhole. This reduces the resistance of key insertion, does not attract dust, and does not stain hands or clothes.