Long Life Coolant Change Intervals?

[willbur]

I drained 11 year old Honda coolant and the observable cooling system parts and coolant looked new. Crystal clear and the coolant voltages were almost unobservable. Similarly 15 yr my old coolant and system in another vehicle looked new, too. I asked myself, why am I doing this?
In my opinion, this was a total waste of time and BITOG paranoia feeds it. Do what the manufacturer recommends and forgetaboutit.

 

[Smokescreen]

Originally Posted by willbur
I drained 11 year old Honda coolant and the observable cooling system parts and coolant looked new. Crystal clear and the coolant voltages were almost unobservable. Similarly 15 yr my old coolant and system in another vehicle looked new, too. I asked myself, why am I doing this?
In my opinion, this was a total waste of time and BITOG paranoia feeds it. Do what the manufacturer recommends and forgetaboutit.


Your experience is close to what I tested with my old 2009 Corolla. I tested it year after year with zero observable degradation in the coolant. Before selling my son the Corolla this year I decided to change out the coolant to provide a fresher start. I went and purchased OEM Toyota coolant (which is only available at their predetermined optimum pre-mixture) and asked the service manager what was the official procedure. Simply draining from the radiator removed 80% of the coolant. I did as instructed I refilled, circulated and tested the coolant again. No change from previous. That coolant was 9 years old and had 330,000 kms (just over 205,000miles) on it.

"Do what the manufacturer recommends and forgetaboutit."

 

[Lowflyer]

Originally Posted by Smokescreen

Your experience is close to what I tested with my old 2009 Corolla. I tested it year after year with zero observable degradation in the coolant.
Yep. I change it too 3/4, inevitable, if I change the tooth belt. All 75000 miles.

With chain drive, without defects on head gasket (contamination), 150k miles is imho a very good reference value.

 

[Railrust]

I would probably say that out of all the fluids in a modern automobile, coolant is maybe the only one I feel comfortable going with the recommended distance/time period. Having said that...it's so cheap and you'll do it so infrequently, why bother to wait? If it's been 6 plus years and 80,000 miles? Just do it.

I'd do simple drain and fills....nothing more...nothing less. Just drain the radiator and call it a day. Then do it again a few years later. Done. Chances are a water pump will go before you ever get a chance to get yourself on a normal coolant changing schedule.

One thing I'd never do is change the coolant from the block. I'm not touching block drains...no thanks...been there, done that.

 

[Lowflyer]

@Railrust
Imho this is near the same

With block all 150k or without all 80k

 

[BMWTurboDzl]

I would just change the factory fill when a cooling system repair is required. Items like thermostats, water pumps, hoses, etc.

 

[DBMaster]

Originally Posted by BMWTurboDzl
I would just change the factory fill when a cooling system repair is required. Items like thermostats, water pumps, hoses, etc.


I add RMI-25 to my system (4 oz every 15,000 miles). I learned about it on this forum. I don't ever plan to change the coolant except in a case like this. If I do ever change it Peak Final Charge will go in and that will be it until the next time the system requires opening.

 

[JHZR2]

I think there's enough objective evidence to justify using the right cooling and just changing it on schedule. Even the Dex in my old 4.3 v6 stays perfect.

It's just a matter of topping up additives. New additives deplete much slower and don't destabilize if used correctly and not blended.

 

[Mad_Hatter]

Reputable mfgs of coolant test their products to various ASTM's relating to coolant & coolant additives to determine performance. They didn't just pluck those service intervals out of thin air.

But if you're getting close to your change interval or you've got some kind of problem with the cooling system that causes you to question the coolant, there are some DIY tests you can do at home. You can test pH using test strips (acids), test the conc of ethylene glycol (freeze/boil pts) using a hydrometer/refractometer and for electrolysis (corrosion inhibitors) using a DMM.

 

[ka9mnx]

You can also test water content in %. I have a tester for that.