After reading all about petrol additives here, decided to try it out myself. So far for the past 1.5 months, I have tried the following:
1. STP Super Concentrated Fuel Injector & Cleaner (Black Bottle)
- Engine sounds & feel smoother
- More responsive throttle
- More stable idling
2. X-1R Engine Treatment Concentrate
- Engine sounds & feel smoother / lighter
- Very responsive throttle
- More stable idling
3. Marvel Mystery Oil Ultimate Engine Performance
- Engine sounds & feel much smoother
- More responsive throttle
- More stable idling
Among the 3, Marvel Mystery Oil is the better product. Can actually feel the improvement almost immediately & it's more affordable & suitable for long run, hence long term enjoyment. For RM 36+ a bottle, can use 4 times while the other 2 cost between RM 20+ & RM30+, 1 bottle per tank & cannot be used often, recommended one bottle every 5000km or so but less than 1000 km later, the smoothness / lightness feel of the engine is no longer there.
As for FC, did felt the improvement after using STP & X1R. On city drive, FC dropped to 0.16 / km from 0.17 while highway drive, FC dropped to 0.13 / km from 0.15
Just started using MMO (since Tuesday), will have to monitor to see if there is any improvement to FC.
Overall, 1 & 2 are worth using as not only it improves the performance slightly, it also helped solved my idling problem.