If the coolant is low it should be topped off with half distilled water and half coolant, if using full-strength concentrated coolant.

Use only coolant that is certified for use in Mercedes-Benz engines. These are usually nearly clear, if perhaps a light orange or yellow in color. They are phosphate-free and are designed not to react with certain metals in the engine. You can use Genuine Mercedes-Benz coolant, or an alternative such as the one pictured.

Be aware that if you use regular green coolant it may lead to engine damage in the long term.

Never mix coolants. If you find your cooling system is filled with green coolant top it off with the same type of coolant but plan to change the coolant out and flush the system in the near future.