Recently had the patrol car (2008 Dodge Charger 5.9 Hemi) in the shop for routine maintenance. The coolant level was low and the mechanic did not have any other coolant than generic "green" EG. He ordered something from the local parts place and it was a DexCool/GM compatible coolant. No mention of HOAT (what Dodge recommends) but the "colors matched" as the mechanic says so he topped off with it. I was skeptical and told him to just top up with distilled water, but he insisted on pouring it in. What I want to know is how compatible is this mix? I know that adding non-DexCool to DexCool filled units can cause problems. Would this be the case with my situation? Am I due for some serious cooling system trouble and will get a new car out of this? TIA.