Hi Yen-Hsen Liem,
Only comment from me is:
Change your oil at 5,000 and use synthetics. While changing conventional oil at 3,000 is good, it isn't as good as it could be.
I will actually go further ... change your oil at 10,000 and use synthetics ... change the filter every 5,000 ... and, this will still be better than changing convential every 1,000.
In this case, there is no substitute for technology.