Originally Posted by ramblinche81
In short, no....that is a waste of time and an abundance of waste generation for a low risk issue related to old fluid.
Drain old, there isn't 1% of old fluid remaining pooled in the system.
Fill with water, circulate for a couple minutes DO NOT ALLOW TO HEAT UP with straight water.
Drain...there isn't 1/1000 of original coolant remaining and it is biologically harmless at this stage.
Fill with proper 50/50 mix and away you go.
actually I would greatly disagree with what you said. The cooling system on the xterra holds 11 5/8 quarts of coolant. Thats almost 3 gallons of coolant. Unless you pull the plugs on the engine block you are not going to get anywhere near that much out of the system. And most people arent going to go through the trouble of pulling the 2 block plugs to drain it completely. You will be doing good to get half the coolant out of the system by draining the radiator. So after a drain and fill and another drain you are still going to be looking at an absolute best case scenario of 20-25% of the coolant left in your system that is still sitting 50% full of fluid. That is assuming the car ran long enough to mix the water and remaining fluid well.
Does this mean you need to continue to fill and flush to get it all out? I would say no, but if you really want to get the system clean and get a proper level of coolant put back in the car you really need more than a 50/50 mix after a single flush. One flush would leave you with 20% mix in half the system and 50% mix in the other half. So again best case scenario you end up with about 35% concentration of coolant in the system. what I do is drain the radiator twice, fill with 50/50 after the first drain let it run for a bit and drain the system again and fill with 50/50. and then after about 2 weeks I drain again and refill with 50/50. Is it overkill, possibly, but I am also the kind of guy that uses distilled water for flushing the system. never understood buying high dollar coolant that is vehicle specific to stop corrosion and then using a water hose to flush your system.