PepBoys sells RedLine Diesel Fuel Catalyst. I have not found it at any other chain stores around me, but some specialty, high performance supply stores sell the full line of RedLine stuff. I think you can find a local supplier by going to the RedLine website (www.redlineoil.com).

Black smoke is generally a sign of unburned fuel, due to poor combustion. The most likely causes of poor combustion are poor injector spray pattern, injection timing off, poor fuel quality, air intake restriction (like a clogged air filter) or low compression. There are bunch of reasons for most of these issues. RedLine will help solve some of them, but it will not address real, mechanical issues. I use it regularly, and it should make some difference. But if you have a really nasty case of smoking, you may have to address the mechanical items to get the machine running as it should. Good luck, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)