China isn’t a member but IEA requires its 32 members to have 90d stockpile worth of oil imports:

https://www.iea.org/data-and-statistics/data-tools/oil-stock...

China is much more cagey about the exact levels and capacity of it's version of the SPR but there's a lot of evidence they're drawing pretty heavily from it to cut their oil imports which has had a big impact on reducing the impact of the whole illegal war in Iran situation.