Overview
- OpenAI began the rollout this week, and on Thursday it made GPT‑5.6 Luna the default for Free and Go ChatGPT users while saying unlimited text chats will arrive next week.
- Plus and Pro subscribers already have an updated GPT‑5.6 Sol in ChatGPT plus a new reasoning slider that lets users choose faster replies or more in-depth answers.
- The unlimited-chat change applies only to plain text messages; file uploads, images, voice, image generation, and other non-text tools remain rate‑limited.
- OpenAI published internal tests showing Luna cut factual errors by about 62% and Sol by about 68% versus GPT‑5.5 Instant on financial, medical, and legal prompts, but outside reviewers note the company did not release the prompts or full baselines for independent replication.
- The update adds teen-focused guardrails and clearer product splits—Chat uses the Chat‑tuned Sol while Codex and ChatGPT Work keep their existing Sol versions—which matters for developers, businesses, and people who must test prompts where they will actually run.