I never feel the need to drain the engine until it's bone-dry. A drain and refill should be sufficient since you are replacing some old stuff with new/fresh stuff.
If you use the drain at the bottom of the radiator and open the cap and bleeder plug, you collect a little over a gallon.
At this point I add a coolant/antifreeze mix of 50/50 to equal what I drained out.
Do it a few times if you want to get as much old stuff out as possible.
Again, in normal service it's just a dilution process. No need for cleaners or a "flush" unless you are certain you have some bad stuff that needs to be gotten rid of.
Then you find the drain plugs on the block to completely drain it. Caution:
they can be a pain to properly service and can end up being a source of leaks in the future.
My suggestion on coolant service:
- No need for a flush or chemicals if the system is operating normally.
Just use 50/50 mix. Either you do it yourself or you buy it premixed.
- You can buy a tester kit to tell you how close to 50/50 your mixture is.
- Color usually shouldn't matter, but you have to ensure the chemicals are correct. I use Prestone. It is green and compatible with both blue and green Nissan coolant.
My advice is to just go buy coolant from Nissan if you are unsure of the colors and mixing. That way you don't risk causing major problems that $50 of "proper fluid" could have avoided.
Here are the part numbers - https://forums.nicoclub.com/post6781535.html#p6781483