2008 Mercedes S-Class Owner's Manual - Page 550

Operation Engine compartment To close washer fluid reservoir: Press cap 1 onto filler hole until it engages. Warning! G Washer solvent/antifreeze is highly flammable. Do not spill washer solvent/antifreeze on hot engine parts, because it may ignite and burn. You could be seriously burned. ! Only use washer fluid which is suitable for plastic lenses. Improper washer fluid can damage the plastic lenses of the headlamps. For more information, see "Windshield washer system and headlamp cleaning system" ( page 733). To open washer fluid reservoir: Pull tab of cap 1 upward. Refill the reservoir with MB Windshield Washer Concentrate and water (or commercially available premixed windshield washer solvent/antifreeze, depending on ambient temperatures). ! Always use washer solvent/antifreeze where temperatures may fall below freezing point. Failure to do so could result in damage to the washer system/reservoir. 549