I'm sure that "oilman" will be along soon to wax lyrically about, and extol the virtues of, the expensive oils that he sells.
Undoubtedly if you've got a new car that you intend to keep for a long time, or one that has been modified to produce a lot more power than standard, using the best oil available, and changing it regularly is to be recommended.
However if your car is of unknown origin, fairly stock power levels (no more than BPU) and/or high(er) mileage, then starting a regime of using eye wateringly priced, designer oil, is literally throwing your money away down the drain (at the oil recycling centre )
Personally I'd recommend using a brand name fully (hydracracked) or semi synthetic and changing it, and the filter every 3000 miles
Obviously if you're doing trackdays, or live and die at the Pod etc. then you should use the more expensive stuff, but for normal use to and from Tescos and the like, oil meant for Formula 1 cars isn't really required
As for viscosity, Toyota in their wisdom recommend a 10w30 weight oil, so something around that is what you should be aiming at (10w40, 5w40 etc)
Personally I wouldn't advise the piss thin 0w grade variants, but each to their own