I'd end up throwing most of it away as a 1lts bottle of colemans lasts me a few years as I don't run my engines much once I know they run and the Aspen has a shelf life.
Not sure about the "huge" price tag, 5lts Aspen is £28.50, 1lts Colmans £7.50 so only £1.50 a litre difference which is better than £20 of out of date fuel.