Join Date: Mar 2015
Location: Oakland, MI
Thanked 123 Times in 92 Posts
When my DEF gauge needle touches the red, I add 2 1/2 gallons which pushes the gauge to full. I don't think the gauge is accurate or linear.
2015 3500 LongHorn CC, 4x4, SRW, CDT, 68RFE
2013 1500 Laramie CC, 4x4, 8 speed