Squeaky keys are a common occurrence in keyboards, most often on the larger keys. This is often due to the stabilizer bar beneath the key cap needing to be lubricated. There are a variety of lubricant options and most work fine, but we recommend you avoid WD-40 and silicon sprays as they contain petroleum-based solvents that are known to damage plastic. Many people report success using either a white lithium grease or a synthetic grease like Super Lube. A squeaky key is an easy problem to fix and you can lubricate the key yourself by following the tips in the video below:
Update: Several people have reported to us that in order to fix their squeaky key, they lubricated the white plastic hooks underneath the key cap as they were rubbing against another plastic part. We recommend you try this if our suggestions don’t eliminate the squeak.