I purchased Corolla Gli 2020 model manual variant and I used 5w-20 as it was used by the previous owner. I also did 3 oil changes on that grade; car ran fine with my driving style gave fuel economy of around 15KM/L. Car was 16000KM on ODO when purchased. I read manual and a video which says 5w-20 will ruin the engine in the long run.
I decided to use 5w-30 and selected Total Quartz 5w-30. I would say one of the best engine oil in Pakistan. Car's acceleration has increased, fuel economy is now 16+ on highway at 100KM/h speed. All I want to say it use recommended oil grade for your engine and don't just listen to any mechanic unless your car's engine isn't in good shape.
Even after two oil changes, car performance is same, still getting 16-16.7KM/L on long routes, calculated from tank-to-tank numerous times.
