Brother if the engine oil, brand, grade, etc. is working absolutely fine, and you are not facing any issues with the engine or engine oil, IMO, you may continue using it, however:
Toyota is good, but Total is better than ZIC IMO! 
If you want to switch, then switch to Total instead of Toyota, and in Total, only pour Total Quartz 9000 Future Series 5w-30 engine oil grade only! Neither less (like 0w-20; 5w-20 is not offered here by Total locally), nor more, like 0w-40, etc.
I hope. It helps. Thank you.