Ad Blue level ?

[OxonCalifornia]

Agree with Skiver. Unless you are planning a massive journey into the back of beyond, wait until the low AdBlue warning appears and then bang in a full 10 litre container of fresh Adblue or use an AdBlue pump at a petrol station that has one..

Definitely .. if you can afford to own a Cali and you are worried about the overall costs of an occasional Ad blue 10L top up something can’t be quite right ?

 

[GrumpyGranddad]

Since AdBlue is Urea, you could make your own

A novel two-step process of forward osmosis (FO) and membrane distillation (MD) was developed to recover the urea in fresh human urine. Specifically, FO was used to selectively separate urea from the other components in urine and MD was used to concentrate the separated urea.