Low coolant concentration for multiple-times flush?

[GlennC777]

I read frequently about people changing from one coolant to another by using mutliple iterations of distilled-water drain/fill cycles, the idea being to iterate until the drain fluid is completely clear.

This seems as though it would inevitably lead to some corrosion in the system since aluminum can corrode VERY quickly when no corrosion inhibitors are present.

I'd rather flush using a safe but low coolant/distilled water concentration. Do perhaps 5x drains/fills over a 1-2 day period with the system heat-cycling each time to allow the new fluid to reach equilibrium throughout the system.

Are my concerns misguided? What lowest-concentration of coolant would be suitable to prevent corrosion over that short period. I was thinking perhaps 10%?

I can't find data on this or similar question having been asked previously.

My goal is to switch from a 2EHA-containing coolant to one without (Peak Asian Blue or equivalent) and reduce the quantity of the 2EHA component to a negligible level.

 

[Snagglefoot]

Yes, keep a small amount of coolant in the distilled water otherwise it will not be totally clear. I’ve witnessed that myself.

Want the best coolant? It’s Prestone MAX, good for 15 years and contains 2EHA. Flame suit on.

By the way, Peak now sells products containing 2EHA. Also, Prestone Asian Blue contains 2EHA.

 

[User_19876]

I read frequently about people changing from one coolant to another by using mutliple iterations of distilled-water drain/fill cycles, the idea being to iterate until the drain fluid is completely clear.

This seems as though it would inevitably lead to some corrosion in the system since aluminum can corrode VERY quickly when no corrosion inhibitors are present.

I'd rather flush using a safe but low coolant/distilled water concentration. Do perhaps 5x drains/fills over a 1-2 day period with the system heat-cycling each time to allow the new fluid to reach equilibrium throughout the system.

Are my concerns misguided? What lowest-concentration of coolant would be suitable to prevent corrosion over that short period. I was thinking perhaps 10%?

I can't find data on this or similar question having been asked previously.

My goal is to switch from a 2EHA-containing coolant to one without (Peak Asian Blue or equivalent) and reduce the quantity of the 2EHA component to a negligible level.

What’s the vehicle and the current fill?

 

[xspeedy]

I don't think the cycling needs to be over days but just a couple of hours. I just did distilled three or four times until clear and then ran the final fill. I heated up the engine at idle with a few revs with heater running to ensure the heater core was included. I don't think I was changing coolant types though I'm not sure driving around would have yielded much benefit.

 

[GlennC777]

What’s the vehicle and the current fill?

More than one vehicle ultimately, but say Honda four-cylinders, K20/K24. First/current subject a mid-oughts K24. I assume anything said would apply broadly to pretty much any vehicle factory-equipped with Honda Blue Long-Life coolant?

By the way, Peak now sells products containing 2EHA. Also, Prestone Asian Blue contains 2EHA.

My understanding though is that Peak, Zerex, and Supertech Asian Blue are all free of 2EHA. Intend to consider those three interchangeable and use lowest-cost option depending on current sales etc.

Want the best coolant? It’s Prestone MAX, good for 15 years and contains 2EHA. Flame suit on.

Wouldn't the best coolant be one that doesn't eat plastics and gasket materials? Or is the 2EHA paranoia overstated? Need I even bother?

I don't think the cycling needs to be over days but just a couple of hours. I just did distilled three or four times until clear and then ran the final fill. I heated up the engine at idle with a few revs with heater running to ensure the heater core was included. I don't think I was changing coolant types though I'm not sure driving around would have yielded much benefit.

Would there be a difference? If so I could accelerate the schedule but for convenience I'd just do a drain/fill after each drive until I'd done it enough times to get a clean drain. Figure a couple drives/heat-cycles per day, maybe three. But even if done consecutively/immediately, wouldn't pure water be risking corrosion?

 

[Snagglefoot]

More than one vehicle ultimately, but say Honda four-cylinders, K20/K24. First/current subject a mid-oughts K24. I assume anything said would apply broadly to pretty much any vehicle factory-equipped with Honda Blue Long-Life coolant?

My understanding though is that Peak, Zerex, and Supertech Asian Blue are all free of 2EHA. Intend to consider those three interchangeable and use lowest-cost option depending on current sales etc.

Wouldn't the best coolant be one that doesn't eat plastics and gasket materials? Or is the 2EHA paranoia overstated? Need I even bother?

Would there be a difference? If so I could accelerate the schedule but for convenience I'd just do a drain/fill after each drive until I'd done it enough times to get a clean drain. Figure a couple drives/heat-cycles per day, maybe three. But even if done consecutively/immediately, wouldn't pure water be risking corrosion?

Pure water will cloud over almost instantly if it has a cast iron block. Aluminum block not so much.

The plastic and gasket issues were on grandpa’s 1990 Chevy. That’s 36 years ago. Time to hike up the suspenders and move on. Prestone’s coloured coolants all have 2EHA.

Prestone’s 15 year guarantee is for products containing 2EHA.

 

[SC Maintenance]

Yes, keep a small amount of coolant in the distilled water otherwise it will not be totally clear. I’ve witnessed that myself.

Want the best coolant? It’s Prestone MAX, good for 15 years and contains 2EHA. Flame suit on.

By the way, Peak now sells products containing 2EHA. Also, Prestone Asian Blue contains 2EHA.

Why do you think it is the best? Honest question?

 

[Snagglefoot]

Why do you think it is the best? Honest question?

For all makes. 15 year guarantee.

My 2008 Chevy Suburban has had Dexcool in it for 18 years ( original owner) with Dexcool containing 2EHA. Original radiator, original water pump, original heater core.

 

[Capt W]

Why such a complex process to flush & drain the system? Pull the hoses and the block drain plug(s) for a complete drain, and flush/drain the heater core(s) separately. I adapt the "blow" function of my shop vacuum to lightly blow water from the latter.

I do the exact same thing for every cooling system service and am always able to fill systems to listed capacity with my selected 50/50 mix.

I also use my garden hose to flush the systems. As long as you're not using super-high mineral content water (such as from a well), any trace minerals that might be left behind are negligible.

 

[The_Jeff]

If you're doing this, get a refractometer and measure the concentration of what you rinse. You should be able to get a couple "free" rinses with enough leftover antifreeze to meet your 10% goal.

Then, once you're below 10%, do you really need to keep flushing? If you want to do your plan, kick it off once you get below an initial 10%. If you know how much you'll use in the final fill and know how much of a jug you have left over, that might make a good intermediate stage.

I have done flushes like yours, daily, with water, for a week and got what I felt was a lot of junk out.

 

[GlennC777]

Why such a complex process to flush & drain the system?

KISS principle, ease of it. Also anybody who's had an engine apart knows you never get everything out, not usually even close.

Then, once you're below 10%, do you really need to keep flushing?

That's sort of my question to the board. One of them, anyway. How much purity is productive to achieve? How much 2EHA left in the system will do damage.

Pure water will cloud over almost instantly if it has a cast iron block. Aluminum block not so much.

Aluminum corrodes differently, I doubt it has to discolor the water at all to have a surface layer of corrosion on internal parts that will affect heat transfer and serve as crystallization sites for corrosion to advance more easily in future.

For all makes. 15 year guarantee.

That doesn't impress me. Even considering that some corporate guarantees are near-worthless, fifteen years isn't really that much if you then need to replace every piece of the system (worst case). I want true lifetime protection against corrosion, hope to keep the car another twenty years (we'll see), and don't see any reason not to use a chemistry the OEM (Honda) trusts and recommends.

 

[SC Maintenance]

For all makes. 15 year guarantee.

My 2008 Chevy Suburban has had Dexcool in it for 18 years ( original owner) with Dexcool containing 2EHA. Original radiator, original water pump, original heater core.

2EHA is great if your engine is designed for it. I won’t use it on anything that isn’t specifically.

 

[Snagglefoot]

Why such a complex process to flush & drain the system? Pull the hoses and the block drain plug(s) for a complete drain, and flush/drain the heater core(s) separately. I adapt the "blow" function of my shop vacuum to lightly blow water from the latter.

I do the exact same thing for every cooling system service and am always able to fill systems to listed capacity with my selected 50/50 mix.

I also use my garden hose to flush the systems. As long as you're not using super-high mineral content water (such as from a well), any trace minerals that might be left behind are negligible.

Hardly anyone opens a block drain or can even reach it.

2EHA is great if your engine is designed for it. I won’t use it on anything that isn’t specifically.

And that’s all good. However, Prestone makes specific colored coolant for all the different models all in the Prestone MAX 15 year Category. They all contain 2EHA. Time to move on?

 

[Snagglefoot]

The phone’s ringing. It’s the head chemist at Prestone.

 

[GlennC777]

The phone’s ringing. It’s the head chemist at Prestone.

Okay, then. What is Prestone's head chemist saying?

 

[Snagglefoot]

Okay, then. What is Prestone's head chemist saying?

2EHA is currently the best corrosion inhibitor available for all makes, yet some people are scared of it. His words.

Believe what you will and good luck.

 

[GlennC777]

You could have just said that without the drama. I'm not a chemist so I look for wisdom from people who know more than I do, in this case the consensus of the knowledgeable seems to be to avoid that compound unless specified for your particular system. Consensus is usually a good guide unless you have special knowledge, which I don't.

If you have good reason to believe the 2EHA chemistry is BETTER for a K20/K24, long-long term (as in indefinitely) than the recommended Honda fluid, considering all effects including on gasket materials and plastics, I wish you'd just spill it.

 

[oil pan 4]

Nope I'm using water

 

[Brian123]

Hardly anyone opens a block drain or can even reach it.

On my car the passenger side block drain is easy to get at, but the driver's side is a nightmare. If you have a 22-year-old car, can the block drain be easily opened?

 

[thastinger]

Maybe I'm not understanding the coolant system layout of your vehicle, but on all of mine, I've removed the thermostate and the larger block to radiator hose and you can flush and pour the new coolant straight through the block. Obviously reattach the bottom hose, fill with hose water, rinse & repeat until you are satisfied, drain again and switch to the distilled water mix.