i've flushed my radiator before w/ castle super flush and it looked pretty clean and still runs really cool(stock 180 thermo, run <180 all the time) but it is still dirty, should i just drain rad. and block also? what is proper procedures for this?????

 

I would do a couple of cycles. Fill with water, run car with heater on max till temp is up, empty rad. After about 3 times I would say you got most of the old stuff out. You could remove both drains on block but the knock sensor one can be a bitch to remove without destroying it.

Jeff D.