The invention relates to a polymer composition comprising polyolefin (a), which is other than low density polyethylene (LDPE), and polyolefin (b), which is an LDPE polymer and obtainable by a high pressure process which process comprises the steps: (i) compressing one or more monomer(s) under pressure in a compressor, using a compressor lubricant for lubrication, (ii) polymerising a monomer optionally together with one or more comonomer(s) in a polymerisation zone, (iii) separating the obtained polyolefin (b) from the unreacted products and recovering the separated polyolefin in a recovery zone, wherein in step (i) the compressor lubricant comprises a non-mineral oil; a power cable, e.g. of a direct current (DC) power cable, use of a polymer composition and a process for producing a DC power cable.