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.
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.