Date registered: Aug 2002
Vehicle: '85 2.3-16 '99 C280 '11 GLK350
Location: Scottsdale, Arizona, USA
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
RE: grill discolored
First, rule out a plating defect with some metal polish. Eagle One has a can of "wadding" that contains a polish for metal parts, but other brands work as well. All polished metal parts that don't have a clearcoat, like chrome or polished aluminum wheels, will oxidize and tarnish.
If the metal does not brighten up with a cleaning and polishing, it may be time for new grill trim. I don't know the pricing for the 99 SL, but usually trim pieces are fairly inexpensive.