Dont judge a engine by its color. The way to tell if its the better one is by the location of the clutch lever (if it is on top of the case = good if it is on the front of the case = not as good) some of the best ones you can get are painted black.
All these china bikes have quality issues (think about it, a decent push bike costs as much as these chineese bikes) even the top of the range motoverts, terra motos and pitster pros so to expect a $700 bike to perform faltlessly is a bit much to ask.
If you want a top bike you need to spend top $$$$ and get a jap one.
In answer to your question. Burning a bit of oil is not going to be high on your list of things that can go wrong (just top it up before you go riding).
Blown shocks, bent rims, leaking forks, not starting, things falling off when you are miles from your car will all piss you off more than using 0.50c worth of oil every few tanks of petrol.