Not sure if this should be in the dumb questions thread, but I'm trying to flush my coolant. I get the process and watched videos and DIY on this thread, but I'm wondering what the numbers and ratios are meant with antifreeze like "50/50". Mixture wise for the end result of having coolant, does this mean having 50 antifreeze/ 50 water or can I simply use FL22 for the coolant?

 

You're safest bet is to use premixed FL22 (no diluting needed) from Mazda and since we only need to change it every 2 years or 30K miles - cheap insurance.

the ratios are by volume (so mix 1 liter of straight undiluted coolant with 1 liter of DI water) per the ASTM D 1122 method.

 

Simply use FL22. IIRC around ￥20 a bottle from dealer.
Fl22 is already a premixed coolant.
Reason is:
https://www.rx8club.com/series-i-tec...licone-238638/
In short, coolant contains 2EHA can cause a blown coolant seal.

 

I think every 2 years is pretty overkill for modern coolant. This is one instance I say go with the factory schedule of 10 years then every 5 years.

As long as it has the lubricating properties and anti-corrosion protection you are fine. I had mine for more than 2 years and just never saw the need for a flush.

 

I'm erring on the side of caution - making sure my FL22 in the car has optimal seal lubrication and chelants to prevent film formation on the metal parts that will reduce the heat transfer capability of this finicky engine. In my other cars (2002 CRV, 92 Integra GS-R, etc) I'll stick by the ~ 50K miles or 4-5 year rule. I also change the transmission fluids (and power steering fluid on those hydraulic systems) out at the same time as the coolant. My 1992 Integra GS-R lasted as long as it did due to my cautious maintenance program (new 2nd owner still has it). I have a friend in California that has been doing the same on his NSX - that car is in great shape.

 

It's almost like the maintenance schedules were written by... some kind of engineers, who.... study the problem? It's basically magic.

 

To be fair, some of the maintenance schedule is a bit too long, like if you use conventional oil, you are not gonna wait to change it every 5k miles.

Coolant change is more involved than an oil change, though. I doubt the buildup is a huge issue until your coolant looks like cola. My coolant was still the nice deep green colour FL-22 has.