I use Oracle linux 5.11 on some PCs because I need old version of gcc for software testing and Oracle 5.x offers a newer kernel than the other RHEL clones.
Last time I tried the Package Updater, it fails with a heap of conflict messages like this:
file /usr/include/asm-generic/fcntl.h from install of kernel-headers-2.6.18-402.0.0.0.1.el5.x86_64 conflicts with file from package kernel-uek-headers-2.6.32-400.36.8.el5uek.x86_64
file /usr/include/asm-generic/ioctl.h from install of kernel-headers-2.6.18-402.0.0.0.1.el5.x86_64 conflicts with file from package kernel-uek-headers-2.6.32-400.36.8.el5uek.x86_64
If I only select one update (kernel-uek) it will proceed, but plain kernel will stumble.
I am only using public repositories, not subscribed to ULN.