Fayat Bomag BP 25/50 Operating Instruction, Maintenance Instruction page 63

Maintenance – Fuels and lubricants
8.2.2.2 Fuel stabilizer
66
If the machine is only occasionally used (if it is out of use for longer
than four weeks), mix in the correct amount of fuel stabilizer
directly after you have purchased fresh fuel.
The fuel stabilizer has a limited shelf life.
Please follow the instructions of the manufacturer concerning the
correct mixing ratio and shelf life.
Mixing in fuel stabilizer does not regenerate old fuel.
BP 25/50