The VC9 is an additive to boost the nitrate levels. If you have not done so check your degas bottle with a test strip. I used John Deere brand to determine the Molybdates, Nitrates, and the Freeze Point levels. At 40K miles it was good to -30 degrees but the Nitrates were less than 300 ppm. The Molybdates we almost non-existant.
I ended up going to my dealer and doing the drain, flush and fill route. The whole thing took 1.5 hours and cost me $147 plus tax. I learned my lesson. I will check every year and add VC9 if the Nitrates are between 300-800 ppm. Maybe next time I will pospone that flush for 3 years insted of two.
BTW, they noticed the DPF and EGR gone when the engine light came on immediately after they pulled it into the shop. I watch the tech kneel down and look under the passenger side door. He looked up at me from 50 feet and smiled. As it turned out I reloaded the stock tunes, being afraid to lose my custome one if the dealer put it on the scan. The truck went into regen as soon as the tech drove it back to the garage. Go figure. I saw a lot of blue smoke when he took off with the distilled water flush in it. At that point I thought the gig was up.
Later the Service Manager asked me if I wanted them to correct the check engine light. I said "no thanks". He asked me what tune I was running, with a smile and winked he said "don't sweat it, everthing's cool" Not a bad morning!
2010 F-350 4x4 CC LB Lariat 3.55 11,500 GVWR oh and the 450 RCD tune to boot