When I had my Mercedes, I used this on the outside locks to prevent them from freezing up in the winter.

Mercedes-Benz Lubricating Grease P/N 002-989-06-51-09 "Schließzylinderfett"

Chip H.

 

My gx470 2009 started not turn the key in all conditions so I sprayed inside the key hole ACF-50. I work with airplanes and this lube/corrotion eater works wonders in switches or stuff that needs lube, doesnt affect electronics if overspray. I sprayed inside the keyhole with the straw/tube and worked the key in and out not taking it all the way out and side to side then it turned, now works fine.