Oils will now never reduce their number of charges, so essentially all oils last forever. The previous mods I saw modified the xml file for oils, which causes conflicts with other mods like Better Icons. It also requires packing the mod into a bundle. My solution relies on script and touches the less often moded damageManagerProcessor.ws.

Works with 1.31, 1.30, 1.22, 1.21, 1.12, 1.11 & 1.10. Just download the version appropriate to your patch level.

Just unzip the contents to your <Witcher Install>/mods folder. Create a mods folder if you don't already have one.