NIC,

I don't put any metal rings inside the oil "containment" when I change the Oil. I use the dipstick sucking device and have all of them left over. When I had my 1975 240D, I had a place for each of the washers though. One went on the bottom of the oil filter (that arrangement was thought of by an evil engineer - the unit was designed to make changing the filter a nightmare) under the bolt that went through the center of the filters and held everything together, one under the pan drain plug and one under the oil cooler drain plug. In the W123 models much of this got "fixed" in that it is much easier to change the filter, and I think the oil cooler drain was eliminated at some point. The washers you get are copper, and they fit under the various drain plugs you may or may not have on your car. I think you get a full compliment of washers to make the washer arrangement of the filter kit non-specific to a model year or chassis number series. Consequently you get washers you don't need. I save them and have about three pounds of copper washers in a couple of bags now. I do not believe any of them go inside the oil flow path. Hope this helps, Jim

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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)