starter motor not cranking

Renault Clio 1.2 petrol mk3 2008 Tried to start the other day, but nothing, ignition all works, no clicking tho Checked battery and obvious things and all fine, managed to bump start and determined it was the starter motor Swapped it today but still doing the exact same thing! Relays seem...

I have engine oil in my header tank & also thick oily sludge in the coolant pipes going from the header tank into the radiator & also into & through thermostat housing... Has been leaking alot of oil on the driveway for some time. Also starter motor is very intermittent, although its almost new...