Some items from the Oxiclean website:
“OxiClean® Versatile Stain Remover works in any temperature water, but best in warm to hot water. Do NOT use boiling water. Please read and follow clothing, carpet, or surface manufacturer’s care instructions for appropriate water temperature.”
“The cleaning strength of OxiClean® will remain active for 6 hours after mixing. Dispose of unused solution after 6 hours by pouring into a drain or toilet.”
So according to their website, soaking for long periods of time might not really be helping.