Nissan 370Z Forum - View Single Post

radensb · 03-02-2025, 12:53 PM

I know, I know - there are many coolant threads and I have been looking through them. I just got done cracking open the timing cover to replace cam phasers and gallery gaskets. I also replaced everything else in there, including the water pump for good measure.

About 5 years ago, I bought new radiator hoses, drain and bleeder o-rings, and Nissan blue 50/50 premix coolant from the dealer. It sat on a shelf until the leak Nissan said was imminent started, but it never did. Fast forward to now and my recent work gave me the perfect opportunity to use those items.

I have an '09 with the green coolant. I got the blue because the dealer said it was compatible and had it in stock at the time. I read on this forum that mixing blue and green means that you have to go by the green coolant life, which seemed like a loss. Also, my green coolant was probably starting to get corrosive as it was VERY old, so I decided to just flush it all out. I used DI water and over the course of 4 flushes, the water was coming out pretty clear (very little green tint).

Once flushed, I filled the car up with the Blue Nissan coolant. I poured both gallons of the 50/50 premix in a 5 gallon bucket and filled the system using a vacuum fill tool. I then put on a burp funnel with more Blue coolant and let the engine run for 15-20 min with occasional revving to remove any additional bubbles. The front of the car was on ramps, which I think helped get the last bit of air out. I also used the vacuum tool and burping method to flush with the DI water. I was surprised to see that the car only took in ~1.25Gal of the Blue coolant as there must have been more water than I thought in they system after I drain from the radiator. Assuming a quart in the overflow container, thats ~ a gallon of 50/50 in the system with the rest DI water, or a 75/25 water to coolant ratio overall.......

Questions:
* Is this ratio actually a concern if I don't live in extreme weather?
My concern is more diluting the detergent and lubrication chemicals in the coolant more than anything. This is my DD and doesn't see heavy use (no tracking and only 78K original miles).

* Should coolant that has been sitting for 5+ years be avoided, even if it was unopened?
I read mixed things about this.

*Should I just drain my 75/25 mix and pop out the block drain plugs to fully empty the system?
I thought that just draining through the radiator was enough, but it clearly leaves more water in than I thought.

Bottom line, I just want to do what is right for the car. I'm not too concerned about buying some new coolant and doing a block drain if that is what is recommended. I read through this very informative post, which does mention the block plugs, but diluted that knowledge with videos that showed the more simple radiator drain and refill. My (faulty) assumption was that a little DI water would be left and a slight dilution wouldn't be a problem, but 75/25 is way more than I thought it would be.

Thanks for the wisdom!

03-02-2025, 12:53 PM	#1 (permalink)
radensb Base Member Join Date: Jan 2014 Location: California Posts: 163 Drives: 09 Nissan 370Z GM M6 Rep Power: 6722	Coolant Flush/Replacement/Conversion I know, I know - there are many coolant threads and I have been looking through them. I just got done cracking open the timing cover to replace cam phasers and gallery gaskets. I also replaced everything else in there, including the water pump for good measure. About 5 years ago, I bought new radiator hoses, drain and bleeder o-rings, and Nissan blue 50/50 premix coolant from the dealer. It sat on a shelf until the leak Nissan said was imminent started, but it never did. Fast forward to now and my recent work gave me the perfect opportunity to use those items. I have an '09 with the green coolant. I got the blue because the dealer said it was compatible and had it in stock at the time. I read on this forum that mixing blue and green means that you have to go by the green coolant life, which seemed like a loss. Also, my green coolant was probably starting to get corrosive as it was VERY old, so I decided to just flush it all out. I used DI water and over the course of 4 flushes, the water was coming out pretty clear (very little green tint). Once flushed, I filled the car up with the Blue Nissan coolant. I poured both gallons of the 50/50 premix in a 5 gallon bucket and filled the system using a vacuum fill tool. I then put on a burp funnel with more Blue coolant and let the engine run for 15-20 min with occasional revving to remove any additional bubbles. The front of the car was on ramps, which I think helped get the last bit of air out. I also used the vacuum tool and burping method to flush with the DI water. I was surprised to see that the car only took in ~1.25Gal of the Blue coolant as there must have been more water than I thought in they system after I drain from the radiator. Assuming a quart in the overflow container, thats ~ a gallon of 50/50 in the system with the rest DI water, or a 75/25 water to coolant ratio overall....... Questions: * Is this ratio actually a concern if I don't live in extreme weather? My concern is more diluting the detergent and lubrication chemicals in the coolant more than anything. This is my DD and doesn't see heavy use (no tracking and only 78K original miles). * Should coolant that has been sitting for 5+ years be avoided, even if it was unopened? I read mixed things about this. *Should I just drain my 75/25 mix and pop out the block drain plugs to fully empty the system? I thought that just draining through the radiator was enough, but it clearly leaves more water in than I thought. Bottom line, I just want to do what is right for the car. I'm not too concerned about buying some new coolant and doing a block drain if that is what is recommended. I read through this very informative post, which does mention the block plugs, but diluted that knowledge with videos that showed the more simple radiator drain and refill. My (faulty) assumption was that a little DI water would be left and a slight dilution wouldn't be a problem, but 75/25 is way more than I thought it would be. Thanks for the wisdom!