Moisture in these caps is a very common thing if these cars aren't used for some time, they don't look so bad but do need to be dried out. The moisture is just condensation from the engines warming and cooling cycles.

__________________
600SEL '91
300E 4Matic '88
240D '83
280SE '77
350SE '73
The most complex systems can fail in the simplest way.
Contra verbosus noli contendere verbis, sermo datur cunctis, animi sapientia paucis.

i don't believe in the lord! He's never bought me a Mercedes Benz.