changing coolant on 2007 2500HD

#1Flyboy wrote:
. . .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. . .

Although color has nothing to do with anti-freeze type or performance, they are not all compatible. I've taken some anti-freeze classes from Staveley to learn the differences between OAT and older typical Ethylene glycol coolants. The type of film and way the film is formed that protects the metals that interact with the coolant are different and you can have serious issues, one of the most serious being Silica fallout. There's a reason why even Valvoline puts this little disclaims in their FAQ section on their antifreeze website:

"Can you mix Dexcool® with other antifreeze products? Link
Improper mixing of coolants has the potential to cause corrosion issues. Valvoline recommends using the correct antifreeze/coolant for your particular application."