Do some more search , the most harm done to the engine is at cold starts.
At cold state , if the viscosity is too high engine might run for several seconds without oil being filled in the engine.
Taglon is a 5w50 , 50 is a good grade for high loads operations and oil will not loose viscocity too early. Results also show that the high temperature viscocity is being maintained or good . But cold start viscocity is bad.
So taglon is doing harm at cold start , whenever you start up your engine in the morning in winters , but is just fine for summers. But i think if they are marketing this oil as fully synthetic , then its not behaving like a fully synthetic oil. the properties have changed so much.
Quote " Start-up engine wear is the wear inside an engine that occurs after the engine has been started and before the engine reaches its highest, normal, operating temperature, which usually takes about ten minutes. It’s widely acknowledged by automotive engineers that most engine wear occurs within this first ten minutes of driving before the engine has reached its highest, normal operating temperature. "