About 14 months ago I had my car mapped for w/m injection , so I bought some premix 5l tubs from Devils own which equated to 25 litres without knowing my mapper had also bought 25l , so now I have 40l left over .

Yes that's right ive only use 10litres in 14 months .
My question is does this premixed stuff go off ?

Cheers

 

Is the devils own premixed with water?if so over time the methanol will evaporate and the concentration will definitely be lower, its a chemical that has a expiry date even unmixed it will start to evaporate drawing in moisture.It can last though for quite some time if it is in a air and water tight proof container,my advice though is only buy enough that you know that you will use up within a certain amount of time so the percentage of the methanol stays purer.SJ.