I recently suffered a radiator failure that led to a dealer replacement radiator with a Motorcraft Gold [VC-7-B] fill in my system without a proper, Gooch-type full flush of the system. I had done the Gooch flush replacing existing Motorcraft Gold with CAT ELC only 8k miles ago. Result is a reddish-gold color, and, obviously, reduced coolant life expectancy given the Ford Gold's limitations. See, for example, Ford TSB 09-08-05, calling for charging Gold with SCA additive [VC-8] depending on test results. I did find a Fleetguard Tech Bulletin [TB-3/05-2, dtd 2005] claiming compatiblity between Fleetguard's OAT ELC coolants [ES Compleat, Fleetcool, etc.] and Ford Gold, CAT LEC, Zerex G-05, etc. The money quote: "there is in fact no technical merit in saying the coolants cannot be mixed." Given this, I lean toward leaving the mix of 'fresh' Ford Gold with some CAT ELC for the next year or two [10-25k miles] before spending the time and money [$100+ for 4 gallons of CAT or Fleetguard ELC] for another Gooch flush'n'fill. Anyone have strong feelings for or against? By the way, I have a coolant filter installed [non-SCA charged] Thx.