Dave, great expectation! I would suggest they do not put anything on the plugs, as they slap them together day and night on an assembly line. If involves an added cost in time/manpower/materials, they will most likely nix it. Another consideration, they make monies repairing the heads when the plugs 'rip out' and break/strip during repairs (back end costs customers incur). And, come on, we do all own a benz/Chrysler red-headed stepchild... I especially like your idea of getting In there and taking them out and putting something on the threads as a preventive measure.
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