Don't flush. My 8v had an engine full of cr ap at 135* when I bought it. I changed the oil every 4k (silver Synta) untl 155k, then every 5k. I just changed oil at 190k and she still pulls like a freight train on viagra.
I reckon changing the oil regularly cleans the cr ap out slowly and harmlessly. Flushing could bug ger all sorts of things up.
KKK