CITROËN DS 5 Handbook page 252

diesel additive level (diesel
engine with particle filter)
A low additive level is indicated by
illumination of this warning lamp,
accompanied by an audible warning
and a message in the instrument
panel screen.
Topping up
This additive must be topped up by a CITROËN
dealer or a qualified workshop without delay.
Used products
Avoid prolonged contact of used oil or
fluids with the skin.
Most of these fluids are harmful to
health or indeed very corrosive.
Do not discard used oil or fluids into
sewers or onto the ground.
Take used oil to a CITROËN dealer or
a qualified workshop (France) or to an
authorised waste disposal site.