TLDR: Many folks seem to have good luck with the stuff so I figured I could give it a try with my Blazer before replacing the heater core. Is this stuff something that should be ran for a week or just a few minutes like other flush products? Thanks. Additional info: My main issue is that I know the system wasn't properly flushed for the transition from Dexcool to traditional green and that it takes forever to get to temperature. (For example, 15*F is horrible.. It takes forever with the heat off and about 7 miles with the heat on.) The thermostat is a NAPA (US made) 195*F. I also want the system clean before going through the hassle of replacing the heater core. I have replaced the coolant twice since ownership and performed 1 garden hose flush. Currently using ST traditional green.