The "white pimples" seem to be caused by salty water drying on a warm engine and starting corrosion as they dry. The as soon as moisture arrives the salt crystals pull it out of the air and corrosion re-starts.

ACF 50 and a dehumidifier both help.


Peter,
66, 2016 Porsche Boxster S
No longer driving Tarka, the 2014 Plus 8...