No additive should void the warranty. I haven't used one yet, but the power service at Walmart is popular, Stanadyne diesel is propular as well for the other big diesels. I might go for the Stanadyne first, but it's impossible to find in the stores.
Hello,
My first experience of the low DEF fluid in my 2014 Ram EcoDiesel. Luckily the truck stop on the route I was traveling had it in stock and I just filled it up. BlueDEF was the brand.