Coolant Change Interval for Hemi Engines

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calinb

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Sep 5, 2016
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Ram Year
2004, 2016
Engine
3.7 6-cyl, 6.7 Cummins
Why not drain/flush to the best of one's ability without resorting to crazy measures, and then refill with water only, start/drive the vehicle until the engine is up to temp and the thermostat is open and then repeat the drain/flush an additional number of times as desired? I'd guess one time is enough to bring, via dilution, old anti-freeze concentrations down to minuscule levels. (Regardless of how many times you repeat this extra flush at operation temperature, there will always be a few old anti-freeze molecules present ;)).

On the final fill with the new anti-freeze, I'd used distilled water if necessary to achieve correct and desired (50/50?) antifreeze concentration levels.
 
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HEMIMANN

HEMIMANN

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Minneapolis, MN
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2017 2500 Laramie Crew Cab
Engine
6.4L HEMI
Why not drain/flush to the best of one's ability without resorting to crazy measures, and then refill with water only, start/drive the vehicle until the engine is up to temp and the thermostat is open and then repeat the drain/flush an additional number of times as desired? I'd guess one time is enough to bring, via dilution, old anti-freeze concentrations down to minuscule levels. (Regardless of how many times you repeat this extra flush at operation temperature, there will always be a few old anti-freeze molecules present ;)).

On the final fill with the new anti-freeze, I'd used distilled water if necessary to achieve correct and desired (50/50?) antifreeze concentration levels.

Well, because it only needs doing every 5 years now. Back when we had to do coolant every couple years, then yes, it was important to save on expense and downtime. Refill with water only risks water pump bearing failure, and I prefer to get rid of rust scale from the cast iron block. I've always seen rust scale from flushed cast iron engines.

If you run until thermostat opens, you can't open the lines or you'll get burned, so either both systems (radiator and engine) need to be drained and flushed with thermostat closed, or the thermostat removed for the entire system. Needs to be one way or the other. With the closed thermostat left in, the entire system should fill from the bottom up assuming all vehicle makers have de-aeration ports in the thermostat housing.

I use the pre-mix antifreeze with distilled water already mixed. Yeah, yeah, I know I'm paying them to mix it, but why not? I'm tired of buying both ingredients and mixing myself in another container.
 

hemihustlin

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Montreal
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2021
Engine
5.7 HEMI
I use the pre-mix antifreeze with distilled water already mixed. Yeah, yeah, I know I'm paying them to mix it, but why not? I'm tired of buying both ingredients and mixing myself in another container.
Yup pre mix coolant is one of those little luxuries in life worth paying for. Whos got time to be mixing and keeping distilled water on hand?
 
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