Here in the uk euro 6 uses a lot more adblue than e5 , plus lots of other unneeded gizmos, I’d your planning on Keeping the truck ( 2nd hand value here will be £10grand plus between e5 and e6 in the same year ) and haven’t got any of the city bans like we have I’d stick to e5 less trouble . E6 a little easier on diesel but that little you hardly notice it .