Acura MDX Coolant Change Interval

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Ok. I have finally accepted a 5k OCI after decades of 3k. BUT, I can not get my head wrapped around leaving the FF coolant in my MDX for 100k/10 years. My last two cars both used Toyota Red Long Life (not the pink extended life). I always did a d/f every 2 years (about 10-12k miles for us)and the cooling system/coolant stayed pristine.

One question I can't find the answer to is why Honda Type 2 Blue coolant FF is good for 10 years but then needs to be changed every 5 years.

Having said all of that, how long should I wait before doing my first d/f? Thanks.
 
I too am tied mentally to the old 24K/2 year change but, I am now going to go out the full 10Year/120,000 miles on my 07 Mazda. I will of course check to see if it looks nasty every other oil change. They are not fools at Honda, so follow their recommendation. Don't have a clue as to who the reduction in change interval after the 10th year. Ed
 
My BMW has had 2 coolant changes in the past 21 years. The cooling system passages in the aluminum head looked like new when I tool out my thermostat.

Do you think you will keep your Acura for 20 years?
 
Originally Posted By: artbuc
One question I can't find the answer to is why Honda Type 2 Blue coolant FF is good for 10 years but then needs to be changed every 5 years.

Because even when you do a correct drain-and-fill by removing the block drain (if your engine is so equipped), there's always a little bit of the old coolant and flush-water left behind. This contaminates the new fill. Factory fill goes into a fresh, brand new, clean block; the factory can ensure there are no contaminants.

Originally Posted By: artbuc
Having said all of that, how long should I wait before doing my first d/f? Thanks.

Do it whenever you feel like it. There's nothing at all preventing you from changing the coolant early. The 10-year coolant thing is like extended oil-drain interval.
 
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The reduced interval on an exchange might also be because they can't guarantee what water is used. That's the reason another manufacturer gives.

It also might be related to the fact that they might not expect you to do a full flush and fill.
 
Originally Posted By: Bluestream
Do you think you will keep your Acura for 20 years?


No, because I am 63 and, at some point, will not be able to do my own service. Hopefully, I will be able to do the first TB/WP job but who knows? I have always kept my vehicles for 13-15 years with rust/corrosion being the limiting factor. I approach maintenance with the idea that I want my car to last forever and I believe rigorous fluid replacement is critical. I do not want to wait until the fluid deteriorates. I want the fluid in the drain pan to be almost as good as the stuff in the bottle.
 
Originally Posted By: Donald
I assume its because if you do a radiator drain you only get half the old coolant out.


Maybe, but why do they say 5years/60k miles on the bottle? You would think Honda would say their coolant is good for 10 years when cooling system is properly flushed and 5 years when doing a d/f.
 
The MDX 100k/10years AF ff interval can be safely followed. I'd go with it with no worries. It's what I've done and plan to continue with my Hondas.

As for why subsequent is 5years, I suspect it's because most, likely do a radiator and drain and fill with Type2. That only gets ~60% or less out of the system.

The other might be, as mentioned, that Honda is less certain of the purity, no minerals, of any water that might be added along the way.
 
Trust me, after corrosion issues with my wifes 2003 MDX coolant system, a 4/50 coolant flush is the longest I would go. Cheap insurance...
 
I like the idea of more frequent drain and fills rather than a 10 year interval where you need to do a thorough flush with plenty of distilled water.

Doing a drain and fill with 50/50 has the advantage of keeping your overall concentration close to 50/50 always. If you wait 10 years, who knows what the concentration is for at least half of that time.
 
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Originally Posted By: RedCorvette
If you wait 10 years, who knows what the concentration is for at least half of that time.

I don't understand your last sentence.
 
The ratio of coolant to water can change and should normally be maintained within a range of 40 / 60 to 60 / 40.

Over time, that ratio would change. Unless you are personally measuring or sure your mechanic is measuring the ratio accurately, and then extracting and topping up appropriately, it is likely to go out of specification. For most people and most mechanics, I am quite confident it is neglected.

The longer it's in there, the more likely it is to be out of spec. I was suggesting that it could be out of spec for a long time if you wait until the 10 year mark to change it.
 
That's true if you don't top off with a 50% mixture. I suppose there are people who don't practice due diligence and only top off with water. Shame on them. Not my cars. I keep at least a quart of 50% mixture on the shelf for top offs.
 
I get a new paper coffee cup and add one of concentrated AF and another of concentrated water. Keep going back and forth until its back up to level. Unless you have a leak, they do not loose much. And some of that loss may really be contraction and colder (winter) temps.
 
Originally Posted By: The Critic
Honda Type II only comes premixed, so the water issue is not applicable.


Bernardi lists the concentrate for sale but I have not checked to see if they really have it.
 
Originally Posted By: Kestas
That's true if you don't top off with a 50% mixture. I suppose there are people who don't practice due diligence and only top off with water. Shame on them. Not my cars. I keep at least a quart of 50% mixture on the shelf for top offs.


But you're also assuming that what is in there is 50/50. Over time, it is changing because the coolant is being depleted.
 
Originally Posted By: RedCorvette
Originally Posted By: Kestas
That's true if you don't top off with a 50% mixture. I suppose there are people who don't practice due diligence and only top off with water. Shame on them. Not my cars. I keep at least a quart of 50% mixture on the shelf for top offs.


But you're also assuming that what is in there is 50/50. Over time, it is changing because the coolant is being depleted.


I believe the additive package for corrosion protection is being depleted but the ethylene glycol is not. EG is quite stable. Yes, a small amount will degrade but not enough to materially change the 50/50 ratio. As I understand it, the additive package stabilizes the EG. As the additive package depletes, some EG breaks down to form acids which cause corrosion. However, the concentration of these acids is very low compared to 50%.
 
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