Jim:

I'm not sure exactly what the stuff is, but it is listed on every container of anti-freeze I've every bought, and MB used to sell it separately -- also heater valve lubricant for the cars with heater valves (W115 and earlier, maybe W123 manual systems too).

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!