Guys Guys! Read my thread above. I own and maintain a 2012 Prius 3rd Gen since Nov 2015 and have been VERY closely watching its performance, fuel economy, and oil consumption.
People talking here are NOT up to date with the current state of high compression fuel efficient engines. Do NOT listen to random posters here about oil requirements.
Virtually ALL hybrids, Prius, Vezel, Civic Hybrid, Honda Fit Hybrid, Corolla Hybrid, and even most non-hybrid modern vehicles RECOMMEND 0-20W oil ONLY. Hence, ONLY use 0-20W oil no matter the mileage!
This is my PERSONAL experience over 2 long years. I am now entering 3rd year of ownership. Let me clarify, I have been diligently using 0w-20 oil (different brands depending on availability) on recommended change intervals. The car has NEVER consumed oil to this date. There was a brief interval that I had to use 5w-30 due to lack of availability of 0-20w and around that time, the economy would hover between 14 km/l - 17 km/l, which is very NORMAL. Our petrol sucks bollocks and that is the MAIN reason our hybrids don't return the economy they do in other countries, so always keep that in mind.
Currently, in its 3rd year of operation in mainly inner city Karachi, the Prius returns a MINIMUM of 16 km/l and is on 0w-20 fully synthetic FUCHS oil. I am on 17" factory fitted alloys. I run a KnN air filter on it mind you, primarily because it sucks in dust very well and is servicable (i.e washable once a year). I initially only used V-power but now use a V-power/Super 70/30 mix. My last tank full has done 160km and the read out says 19 km/l which roughly translates to 18km/l in my experience (trip computer read out is off by 1 km/l).
In summary, all myths associated with 0w-20 oil are busted. ALWAYS use manufacturer recommended oils and ignore the desi neem hakeem mechanic's advice and protect your engine from DUST (air filter), bad fuel, and bad oil at all times
Happy motoring!