I buy the 5 litre cartons of adblue recently. I had been buying the 10 litre cartons but never used a full carton. If adblue carton is opened & has been exposed to air while pouring it into the van can the remaining still be used later. I've a couple of 10 litre cartons in the shed with small amounts left in them that I'm afraid to use in case it crystalised as there's signs of crystalisation around the lid.
Also what's the correct way to dispose of it if I should not use it?
Also what's the correct way to dispose of it if I should not use it?