I use the cheapest stuff I can get my hands on that meets the renault spec, I forget the brand but it's £21 for 20 litres. At that price I can afford to change it every 6k miles. Car is now on 140k and still goes well and doesn't use any oil.
My thinking is, while more expensive oil is probably better in terms of additives for keeping the engine clean, my cheap oil doesn't really get very dirty between changes. The makeup of the hydrocarbon chains is probably more consistent in more expensive oil which will prolong its viscosity and therefor service life, it still doesn't stop it from filling up with <10nm particles over its extended service life which are too small for the oil filter to catch and will cause wear. Changing out cheap oil sooner keeps the wear causing particles at a much lower level imo.