YMMV
While it is true that as a general rule closing your oldest card results in a score drop, the actual number of points varies with your credit status and depends in a lot of factors:
• How many other cards you have, and for how long have you had them?
• How thick is your credit report (i.e. how long is your credit history)?
• What is the limit on the card you are closing, what would be your total utilization after the card is closed?
Length of credit accounts for only 15% of your FICO score, so if you have other cards for a long time as well you can expect a minor drop.