Original post by: Thomas ,
Sorry, Apple has confirmed that the MacBook and MacBook Air models (all) have non-upgradeable RAM. This is regrettable as I also have an Air 11' from mid-2013 and it is entirely inadequate for both Mavericks and especially Apple's latest OS Yosemite. For the record, I do not recommend deploying the latest OS in any situation. It has inherent security flaws that the company refuses to acknowledge nor patch (root kit exploits!).