My experience with B100 and B20 in a 1985 300D-T (W123, OM617) confirms what earlier posters have written. (1) Anything over B5 (some even suggest B2) improves the lubricity of the fuel, especially ULSD, which is about all we have in the states these days. Lubricity is good for the diesel injection pump. (2) Anything from B20 up eliminates the diesel "stink." (The "stinkiness" of diesel is obviously very personal.) (3) Fuel economy is slightly reduced with B100 (1-2 mpg); fuel economy with B20 is not noticeably different from D2; B50 fuel economy I do not know. (4) B100 is pretty solid at 32ºF. If your area gets that cold or colder, switch to a blend. B20 should be close to D2 in anti-gel properties, especially if the D2 portion of the blend is "winter diesel." There are also anti-gel liquids sold in small bottles for high prices at your local McParts store or truck stop. You can experiment by putting samples at various concentrations in your refrigerator or freezer. Remind your wife NOT to use it for cooking.

If the price of B100 were no more than D2, I would be tempted to try B50. Here on the west coast, B100 is more expensive than D2 because it is produced in the Midwest and shipped out here, adding to the cost. Consequently I've standardized on B20, available locally at the pump for $0.10 more than D2, for my two current diesels.

My '95 E300, new to us a year ago, now has 10K miles on B20 and still has un-disintegrated factory-type return hoses. On B100 in the OM617 I found factory hoses lasted about a year so I switched to Viton. A web site called "fryerpower" has a good selection of Viton hose and o-ring kits for Mercedes and other diesels.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970