The oil-change interval printed on your service sticker is a starting point, not gospel. The real answer depends on the oil grade you use and how you actually drive.
Mineral oil breaks down fastest under heat and contamination — plan on 5,000 km or 3 months, whichever comes first, especially in stop-start city traffic. Semi-synthetic stretches that to roughly 7,500 km, and fully synthetic oil, with its more stable molecular structure, can safely go 10,000 km under normal conditions.
"Severe" driving — short trips under 10 km, constant idling in traffic, towing, or extreme heat — ages oil faster than the interval assumes, regardless of grade. If most of your driving is short city hops, lean toward the shorter end of whatever interval your oil grade allows.
Color alone isn't a reliable indicator; modern detergent oils darken quickly even when they're still doing their job. If you're unsure, an oil analysis at your next service is a cheap way to get a real answer instead of guessing.