forte biodegreaser is unbelievably good. a proper flush will need doing over the period of a few days; drop coolant, fill water, get up to temp, drop coolant, fill water, basically do this til clean, then use the forte stuff and run the car with that in for a bit, then drop, fill water, run, then more forte, and so on until you end up with perfectly clear liquid/water without any bits in. then when forte is used up repeat the process but start putting in coolant and eventually the pink will be the right colour (tip: if the engine is producing clear water when draining then put in a strong mix of coolant, maybe even neat, as the v6 lump holds about 50% of the coolant in the system if using just the rad drain plug, so you'd end up with rough 50 50 mix this way. of course, you'll be draining it again shortly afterwards after it's been running anyway so not much chance of doing any damage).
forte biodegreaser can be difficult to find in the stores so fleabay is a good bet.