Does an oversold RSI mean it is time to buy?

No. 'Oversold' is a description of recent price behaviour — losses have outweighed gains by a wide margin over the lookback window — not a forecast that the decline is finished. Stocks in serious downtrends routinely stay oversold for weeks while continuing to fall.

This site scores a low RSI as a bullish lean, and that is a modelling choice with a known failure mode: in a sustained decline it will lean the wrong way for a while. Stating that plainly is more useful than pretending the indicator is smarter than it is.

The 30 line is an inherited convention from the 1970s, not a per-stock statistical boundary. A stable utility might reach 30 only in a genuine dislocation, while a high-volatility growth stock might visit it several times a year in the course of ordinary swings.

Applying one number across a universe of very different stocks is a simplification. It is the same simplification nearly every charting platform makes, and it is worth knowing you are relying on it.

Context is what separates a low RSI worth noticing from one that is simply a downtrend in progress. Is price approaching a support level that has been defended repeatedly, or is it in open space below every detected level? Is volume showing accumulation into the weakness — the bullish OBV divergence case — or is participation confirming the decline?

Is there a trend at all? A low RSI inside a range is a different thing from a low RSI in a stock making persistent new lows with a high ADX. The composite score on this site exists to combine those considerations, which is the reason it does not simply forward the RSI reading.

An oversold reading tells you a move has been one-sided recently. Whether that means anything depends on everything around it — and even with all of that context, technical indicators describe the past. None of this is a recommendation, and no combination of indicators removes the possibility that a falling stock keeps falling.