No, oldfred means basically an equivalent to what the sed script I suggested above does: copy the entries from /boot/grub/grub.cfg that were generated by /etc/grub.d/30_os-prober to /etc/grub.d/40_custom. Those are all the lines between
Originally Posted by firekage
### BEGIN /etc/grub.d/30_os-prober ###
With the difference that in my script, instead of being copied to 40_custom, they were written into /boot/grub/custom.cfg that gets included by /etc/grub.d/41_custom. This way, after disabling os-prober in /etc/default/grub you will still retain all the entries in the boot menu. However, these entries won't get updated anymore when something in in your boot configuration changes. E.g. if you install a new kernel in Ubuntu 12.04LTS, the GRUB from Ubuntu 12.10 won't see it.
### END /etc/grub.d/30_os-prober ###