Overview
- OpenAI announced the change on Thursday and immediately started rolling the Chat‑tuned GPT‑5.6 Sol to Plus and Pro subscribers while beginning to switch Free and Go accounts to GPT‑5.6 Luna this week.
- Free and Go users will get unlimited text chats next week and a new Think button that lets the model spend more processing on harder questions; limits will remain for file uploads, images, voice, and image generation.
- Plus and Pro users receive a revised GPT‑5.6 Sol in ChatGPT plus a slider to control how much reasoning the model applies, replacing separate Instant and Thinking modes with one adjustable experience.
- OpenAI’s internal tests report that Luna made 62% fewer factual errors and Sol 68% fewer errors than GPT‑5.5 Instant on certain legal, medical, and financial prompts but the company has not released full prompts or independent benchmarks.
- The update keeps the Sol versions used by Codex and ChatGPT Work unchanged, adds tighter safety guardrails for users under 18, and follows the June–July rollout of the GPT‑5.6 family as companies and enterprises weigh governance and data‑residency needs.