help with coolant types?

[ansys]

Hi all,
I've been racking my brain with all this research into coolant lately and I'm getting dizzy. I've got an SW20 where the coolant's colour is similar to the urine colour of a dehydrated person (sorry for the analogy), a kind of slightly dark'ish yellow... Is it from one of those yellow "universal" coolants? or is something seriously wrong with the engine/cooling system

I know it's not a good idea to mix certain coolant types because they can sludge up and cause problems (which types are incompatible again?)

Can someone set me straight as to if there's a real difference between the various coolant colours out there these days (red, green, blue, purple, pink, orange, yellow...)? My understanding is it's more of a marketing thing these days, though supposedly the red lasts longer than green? what about all the other colors... some have a different formulation specifically for racetracks I see that keeps them from making the track slick.

Should I stay with OAT or HOAT coolants? does it matter? what's the difference? Most things seem to be phosphate and silicate free these days anyway

I'm pretty sure Type A is the way to go?

also does anyone know anything about how the various Radtech coolants are different aside from colour? I had a chat with a guy in BNT (he was very vague), and checked the website but can find no real difference between any of their variety in terms of technical specifics and compatibility.
https://www.radtechantifreeze.com/

What's so special about Prestone that makes it "universal"?

How low of a concentration can you go? 33% seems to be very common over here (even some of the premix ones are 33!) though I've seen more tropical locations recommend as low as 10-20% even. At what point to the anti-corrosion properties of the coolant become too diluted?

thanks!

[lasersooby]

Have you thought about Evans, the product is supposed to be pretty good and it is waterless too. The only issue will be to get your system dry with no water in it:

https://www.evanscoolant.com/

the other issue is that they are expensive unfortunately.

[Reubenh]

I have never had an issue with your standard green coolant

Just go to supercheap and grab 10l of premix 50% green nulon, add water to suit and it will work out

[Benckj]

Your question regarding coolant is a valid one and often misunderstood by many MR2 owners. This vital fluid is very important to maintain your vehicle and often neglected. For starters I'll attach an older article to read through that describes what the different formulas & colours mean. Many of the parts store salaespeople have no idea about the differences which doesn't help with selection. The comments I've overheard are laughable.

https://www.underhoodservice.com/correc ... confusion/

For an older vehicle like the 3sgte the type of coolant used is not critical. What is important is that once you select the type you stick with it and don't mix with others. While the etholene glycol doesn't deteriorate with age the corrosion inhibitors do. I like choosing a coolant that has inhibitors available so I can add a bottle every couple of years to keep the PH from going acidic and allowing electrolysis occur. I do this with all my cars and run the same fluid to reduce chance of mixing up.