You said this is your First CG-125. I doubt if you are ever going to Actually notice any difference in oils.
If a brand 'works fine' (keyword: FINE) for you ... you will simply tag it as "Very Good". And i must tell you, BOTH Havoline & Zic works brilliantly in Winter Season.
Its the Summer Season where the 'true' performance shows.
I'll avoid doing the "technical" analysis as i am no way qualified enough to do so. However, i'll just share my (and my friends') experience.
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Engine Noise (like, Engine is "Screaming") becomes more Prominent, when Engine Oil gets HOT (i.e. it gets Thinner).
- Clutch Loosens its working (the Worst problem in the History of CG-125 ... obviously because of Wet Clutch) ... and it'll be affected much more incase of a Thinner Oil (or HOT oil).
Thats exactly where ZIC 4T doesn't quite fall upto expectations. Like i mentioned, it works brilliantly in Winter Season. It underperforms the Havoline in Summer season (especially when ambient temperature increases upto 35C)
I have stopped experimenting with Engine Oils and i have been using Havoline since 3 years now. Sometimes, i DO feel the need of a better oil, without caring how expensive it'd be (its usually in Summer Season :P). But overall, i'd rate my experience Quite Well with Havoline.