Instructions
Flip the Zippo lighter upside down and determine if the lighter has the date already stamped. This would signify being made after 2000. If it was made before that year there will be a pattern instead.
Determine what the pattern is on the bottom of your lighter. It is located to the bottom right of the Zippo logo.
Open up your web browser and insert http://www.zippoclick.com/collecting/dateCodes.aspx into your address bar.
Use the website provided to determine when your Zippo was manufactured. For most web browsers you simply need to hit CTRL and F. Once you have brought up the find box, simply type in the pattern that is on the bottom of your Zippo lighter and hit enter.