Dear I won't get in to the debate, but thick oil never kills the engine, as long as its one of the oils mentioned in the owners / users manual.
I have never seen any engine "killed" on using even 20w-50, be it an older engine in Mehran, or a newer engine in PKDM Corolla, as long as oil is authentic, and engine oil + oil filter is changed after regular intervals.
Removing T-Valve, running radiator Fan directly (instead of Auto) when car has even not started, using tap water instead of proper coolant, reviving the engine when it hasn't attained a comfortable operating temperature, etc. actually weaken, and ultimately "kill" the engine in long run.