so this morning i figured i'd pull my heater core and replace it, i figured it would be a standard core swap but i pulled it and a huge OHHH ****!!! followed... when i got the core out it had gunk all in it.. this stuff looked like peanut butter and had the consistency of tar, it was full of this stuff too and this got me worried so i drained the radiator to find a nice thick coating of it has settled in the bottom.. so i now im worried that its found its way into the heads, or other places i dont want it..

is there anyway i can run something through to clean it? this has really got me worried.. i never had problems with it over heating while it was running, but it still worries me

 

I believe Prestone (and others) make a "flush" that's available any parts store.