Key takeaways
What happened
6 Sol and a slider for adjusting response depth. 6 Luna. 6 Sol now cuts unnecessary detail and excess formatting. For simple questions, it delivers a direct answer with just enough context, while more complex tasks get a fuller response that still makes the key recommendation easy to spot. The company also claims better factual accuracy. 5 Instant. Those figures haven't been independently verified. The update only applies to ChatGPT.
Luna may perform well for its size, but smaller models are generally more error-prone and less reliable. A case involving the previous Instant model, which produced a completely wrong data analysis compared to its larger reasoning counterpart, made that risk clear. Since the Think button only lets the smaller Luna reason longer rather than switching to a stronger model, free users lose access to OpenAI's most powerful reasoning altogether.
Why it matters
6 Sol remains unchanged in ChatGPT Work and Codex. A new slider lets paying users adjust how much effort ChatGPT puts into a response. Lower settings suit everyday questions, while higher settings are meant for planning, research, and coding. The slider was already available in ChatGPT Work. OpenAI says it wants quick answers and deeper reasoning to feel like one model rather than two with different tones.
An OpenAI developer recently broke down which of the five settings fits which type of task. The slider works on web, mobile, and desktop. It's worth asking whether these controls actually help people use AI better, though. Users largely ignored the model switcher, and picking the right model for a task likely mattered way more than choosing among five reasoning levels.
What to watch
Adding more knobs to turn doesn't make the experience better. 6 Luna will become the default for Free and Go users later this week, according to OpenAI's release notes. Unlimited text chats and a new "Think" button for harder questions will follow next week, though limits on file uploads, image generation, and other tools will stay in place.