FWIW - I have a few of those big plastic cat litter jugs that I saved from when we had cats. Been using those to put dirty motor oil in for years. There's all kinds of big plastic jugs out there, some thin, some thick, many for free. Ask at restaurants too, some get cooking oil in big jugs. Or, you could just buy a bigass plastic gas can or steel jerry can. Lots of things to store dirty oil in, but I'd never use something that can't be sealed up, like an open bucket.