some oils are going to look thinner when they are cold verses when they are up at opterating temps.
i dont know that we can firmly say that one oil is bad or causes damages verses another one without taking into consideration, driving conditions,maintaining the engine,mileage of engine so on....now thats not to say that one oil has not been reformulated and not as good as before. but you do have to look at other factors to when it comes to engine damage and failure, oil play 1 part that is my opinion.
its not to say that all these damage bearings and rod knocking isnt cuased by high mileage worn out engines ect that would have went even if you were using the best of the best oil...just a thought