Oil Pan repair.
It will cost $5.00 (not $500). Just a suggestion.
I'm also new to the M-B world; I'm a professional fabricator in the performance automotive industry, and as such do a fair whack of welding.
To answer your question, the oil pan may or may not be weldable. Many european manufacturers (VW and Porsche especially, in my experience) are known for using varying amounts of magnesium in their castings. Weld repair of magnesium alloy's is best left those who've done it before, or are at least a) know how to identify it, and b) know enough to research how to weld it. The welding process would be GTAW (aka TIG/Heliarc.) Magnesium alloy filler material is VERY expensive, so keep this in mind if you find a shop who gives you an expensive quote. Bear in mind, it may or may not make for a sucessful repair.
I'll second the suggestion for repairing the pan with an epoxy based filler. JBWeld, and a host of other products will work. Make sure the area to be repaired is CLEAN and oil-free. A little sanding goes a long way, followed by chemical cleaning (acetone, etc.)
It'll at least get you hole-free until you can source another pan from a wrecker/etc.
Best of luck,
Mike



