changing coolant on 2007 2500HD

. . .My questions would be how much was drained out and/or was it truly "flushed" out; how much 100% antifreeze went back in to bring the % solution up to where it should be & did anyone think of also adding a can of anti-rust? (I'd recommend you check your % solution of antifreeze with a refractometer ) All antifreezes are compatible (yes you can mix red, yellow, green & orange & no harm is done; the claim being you get the least amount of corrosion protection of the lowest protection antifreeze)( If you doubt my words PLEASE provide expert published opinion )Dex-Cool has been especially hard on 4 & 6 cyl GM engines but appears to do OK in 8 cyl gas & diesel motors. . .Me, on my 6.6 diesel, & believing Dex-Cool was GREAT for business but not for my vehicles, I high pressure reverse flushed out the Dex-Cool at 52K miles & put in 70% solution of 5 year / 150K mile long life ( Off brand but made by Prestone ) added a can of anti-rust & a bottle of diesel additive.. . Did it again at 100K. . But changed both T-Stats this time. . .Just my humble opinion; please no yelling or rants - don't want to spill my drink. . .Also did all my friends GM vehicles (all have trucks) at 50K miles Everybody is happy. . .