By default, the boot loader GRUB is used in openSUSE. However, in some cases and for special hardware and software constellations, LILO may be necessary. If you update from an older openSUSE version that uses LILO, LILO is installed.
Information about the installation and configuration of LILO is available in the Support Database under the keyword LILO and in /usr/share/doc/packages/lilo.