Where was the sarcasm?
btw - 10 years ago you could walk into any lube shop in Karachi and buy a 5w30 easily - it was the ZIC ke patla wala oil. Problem was that no-one bought it because "patla hai - engine sound maarta hai"
using a thick oil actually is hurting your engine, to understand it you will have to understand how an engine oil system works, what happens to oil in the bearing surfaces etc. Your presented yardstick is "my engine fan didnt work that long and Im not getting knocking from using this oil"
I simply cannot take this discussion further because the yardstick doesnt make sense.
The reason the top of the line oils in every brand are of higher viscosity "spread" is because they are expensive to blend - blending an oil to have a 5W20 viscosity is quite a bit cheaper than blending a 5W60 - that goes into grp IV base stocks and some unique add packs. - very expensive - such oils usually are specced in higher range of engines - not sell by the dozen econocars.
I still fail to understand why would anyone want to waste extra money on running their car - lets take my mercedes - I buy its oils when they are cheap - its maximum oil change interval is about 24,000 kms, 8 litres of expensive euro blend 5w40 or 0W40 oil - Im sure as shine not going to dump it every 5000 kms - Im going to make sure I get my maximum return from it.
I can choose to run it on regular diesel 15w40 oil and dump it every 5000 kms, wont be economical would it?
OTOH I have a camry - I put in dino juice API SN 5w30 - change every 5000 kms - cheap bought in 20 litre drums (for my other cars and also side business of servicing cars)
using the 5w40 in the camry usually results in poor mileage. So why waste money, Toyota spec 5w30, API SL for it - Im putting 5W30 SN oil - it works nice. same with my chevy, nissan and mazda too. (mazda spec 5w20)