Previous owner had STOP LEAK all in the radiator to stop a leak. Found it all over the inside of the oil cap. Head gasket. SHOT. So.... D16z6 from Japan on Friday. I have a new radiator and upper and lower hoses to go on motor. Should I change all the other hoses or do a flush before the new motor goes in? The motor in there now doesn't smoke or even over heat until about 20min. of driving anyway. You think the flush will get everything out of the other hoses? How about the heater core? I just don't want crap in the new motor. Any advice would be appreciated. My first motor change.