A fluorochemical composition for rendering fibrous substrates oil repellent, water repellent, and/or stain repellent and comprising a fluorinated polymer dispersed in water or dissolved or dispersed in an organic solvent, the fluorinated polymer comprising units derived from (i) a mixture of two or more fluorinated polyether monomers that differ in at least their molecular weight, the fluorinated polyether monomers having an ethylenically unsaturated group and a perfluorinated polyether group and wherein at least 90% by weight of the mixture consists of fluorinated polyether monomers that have a perfluorinated polyether group having a molecular weight of at least 750 g/mol and (ii) one or more units derived from one or more co-monomers other than a fluorinated polyether monomer and wherein the co-monomers comprise at least one non-fluorinated monomer. Also, method for treating fibrous substrate with such composition, fluorinated polyether monomers, and fluorinated polymers derived from such monomers.