Has anyone been successful in finding an actual spec from GM in “normal” usage for DEF fluid? I have a 2022 Chevy 1500 duramax 3.0L. It has 3300 miles on it and has used 11.5 gallons of DEF. Dealer says this is normal and also says GM does not have a spec. So how can we know what’s normal if there is no spec. The truck gets 32 mpg without the trailer and 16 with it. My DEF usage is 8% of fuel usage. Everything I find online says it should be about 2% of fuel usage.