The software described in this documentation is either in Extended Support or Sustaining Support. See https://www.oracle.com/us/support/library/enterprise-linux-support-policies-069172.pdf for more information.
Oracle recommends that you upgrade the software described by this documentation as soon as possible.

3.1 Supported Upgrade Paths

On i386 systems, upgrading from Oracle Linux 6 GA or a previous update to Oracle Linux 6 is supported for the Unbreakable Enterprise Kernel Release 2 and the Red Hat Compatible Kernel. The Unbreakable Enterprise Kernel Release 3 is not supported on the i386 architecture.

On x86-64 systems, upgrading from a previous update to Oracle Linux 6 or from Oracle Linux 6 GA or is supported for the Unbreakable Enterprise Kernel Release 2, the Unbreakable Enterprise Kernel Release 3, and the Red Hat Compatible Kernel.

Upgrading from a beta release is not supported.

In-place upgrading from a major version of Oracle Linux 5 or earlier is not supported. Although Anaconda provides an option to perform an upgrade, fresh installation is strongly recommended.

If you have an Oracle Linux 5.8 system, you can use new features in the Unbreakable Enterprise Kernel Release 2 without upgrading to Oracle Linux 6 as Oracle Linux 5.8 includes the Unbreakable Enterprise Kernel Release 2. You cannot use features from the Unbreakable Enterprise Kernel Release 3 as this kernel is not available for Oracle Linux 5.8.