I have a 1999 C230k which I purchased new in 1998 when the kompressor engine was new in that model. It now has 145,000 miles on it has been a very reliable car, except for the supercharger seizing at 100,000 miles. For the first 80,000 miles it used conventional oil and went about 10,000 - 12,000 miles between changes before it was switched over to Mobil 1. The engine has a distinctive noise at slow speeds but is quiet otherwise. It has a lot of power (more than the C280 in my opinion). A very solid, reliable car.

What'd it cost to unseize or replace the turbo?

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1982 240 D, 308,000 - 321,127 miles (sold)
1982 300 TD,166,500 - 226,000 miles
1998 E 320, 120,000 - 144,000 miles
2005 C 230 K, 26,000 - 77,000 miles (sold)

The part was $1,800 and the labor about $200.