Abstract: The invention relates to the use of polymethylalkanes having terminal methyl groups and methylene and ethylidene groups of the formula I ##STR1## in which the total number of C atoms n+2 m+2 is 20 to 100 and the ratio of the methyl and methylene groups to the ethylidene groups is 3 to 20:1 and the ethylidene groups are always separated by at least one methylene group, as biodegradable base oils for lubricants and functional fluids. Suitable polymethylalkanes are obtained by oligomerization of .alpha.,.omega.-diolefins, for example in particular according to P 41 19 332.6, or by pyrolysis of ethene/propane copolymers and subsequent hydrogenation in each case. The polymethylalkanes can be combined with conventional additives and other degradable or non-degradable base oils.

Abstract: A method of manufacturing methylidene-group-containing .alpha.,.omega.-unsaturated oligomers from .alpha.,.omega.-diolefins in the presence of a catalytic amount of organoaluminum compounds, wherein the .alpha.,.omega.-diolefins are reacted in the liquid phase, at 150.degree.-350.degree. C., and the organoaluminum compounds have formula AlX.sub.3 or AlX.sub.2 H, where X represents an aliphatic, alicyclic, or aromatic hydrocarbon group with 1-30 C atoms. The higher molecular weight hydrocarbons manufactured according to this method are substantially linear oligomers which contain reactive double bonds.