CITROEN 2 CV4 1975 Owner's Manual page 21

The level, visible through the transparent reservoir, must never go
below the "Danger" mark. If the level drops suddenly, consult a
Citroën dealer without delay. We recommend the "70 R 3" fluid,
distributed by TOTAL. If this product is not available, use fluids
with specification "S" or "V" : NF R 12640 or SAE J 1703 a.
4 Battery
Check the level of the electrolyte frequently, especially in Summer.
Fig. 32a
The level should be 3/8 to 3/4 in. (1 to 2 cm.) above the plates in
each of the six cells. Top up with distilled water. Never add acid.
RHD Levels Never bring a naked flame near a battery during checking.
3 - Brake fluid level
5 - Windscreen washer bottle
5 Windscreen washer
Top up with clean water, to which may be added a product such as
"Clearalex", "Screen Clear" or "Stop-Clair" at any time, or a
solution such as "Stop-Gel" in Winter.