When it comes to a Linux kernel - the newest is not necessarily the one you want. As the kernel number climbs upward, this means that the kernel version includes patches or additions for newer software. If you are running an older machine- those additions would mean nothing to you. The newest Kernel is also rolling release - which means it may have Fresh new Kernel bugs and issues that have yet to be ironed out.
As long as a computer works properly on an older kernel - then that is the kernel that you want. Upping to the newest, just for the sake of seeing a bigger number on your kernel, can actually lead to problems. Let the vetted kernel come to your system from the developers that have tested it in order to have the best results.