wouldn't the astm spec for B20 (or any other blend of biodiesel) keep the level of glycerin, soaps, methanol, water, etc. low enough for that not to be an issue

wouldn't the astm spec for B20 (or any other blend of biodiesel) keep the level of glycerin, soaps, methanol, water, etc. low enough for that not to be an issue? I thought methyl-esters as a solvent would be better for the the engine anyway. But I had a guy tell me two weeks ago that he uses B100 in his new Mercedes wagon despite its 'blue tec' technology.