Oracle will no longer release ASMLib kernel drivers for RHEL 6 kernels. See this note on support.oracle.com
Oracle ASMLib Software Update Policy for Red Hat Enterprise Linux Supported by Red Hat (Doc ID 1089399.1)
Going to Oracle EL 6 is an option, and may save money in the long run, one vendor to support OS and database. Oracle is much closer to the drivers that are used for database purposes exclusively, and support may actually be less expensive.