My new. Car is now showing it’s time to top up the Ad blu. 

Is there any difference in quality between brands or shall I just buy cheapest I can find? 

Do I have to fully top up or can I just add a gallon ? 

Probably stupid questions so I apologise in advance. 

If called 'AdBlue'  then that is what it is as that is a trademark and it will be the right stuff.

Just buy at trusted sellers.  Filling stations pumps being nice and easy.

 

A gallon will be OK, but how much does it say you can add?

 

Just take care not to overfill or to spill any, and if you do spill clean up carefully.

Maybe a good idea to leave the level just a bit less than full.

Edited 29 June, 20188 yr by Offski