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Why does radiator coolant need to be replaced? #4243778
11/07/16 11:41 AM
11/07/16 11:41 AM
Joined: Nov 2016
Posts: 479
MN, CA
veryHeavy Offline OP
veryHeavy  Offline OP
Joined: Nov 2016
Posts: 479
MN, CA
My car passed 60,000 which means I need to flush the coolant.
But why?
It still looks nice & green. It feels like I should be able to run to 120,000 since the radiator still continues to keep the engine from overheating. What exactly happens to coolant that it requires replacement after 60000 miles of usage?

Last edited by wwillson; 11/08/16 06:14 AM. Reason: subject spelling
Re: Why does radiator coolant need to be replaced? [Re: veryHeavy] #4243784
11/07/16 11:45 AM
11/07/16 11:45 AM
Joined: Nov 2008
Posts: 12,527
NH
supton Offline
supton  Offline
Joined: Nov 2008
Posts: 12,527
NH
The corrosion inhibitors give up. What mechanism that is, I dunno (what wears or gives out). But due to the dissimilar metals in the system, once those inhibitors go, so does precious metal.


2011 Toyota Camry, base, 2.5L/6MT, 163k, hers
2010 Toyota Tundra DC, 4.6L/6AT, 144k, ours
1999 Toyota Camry LE, 2.2L/4AT, 190k, his
Re: Why does radiator coolant need to be replaced? [Re: veryHeavy] #4243791
11/07/16 11:50 AM
11/07/16 11:50 AM
Joined: Mar 2008
Posts: 5,840
South Florida
bubbatime Offline
bubbatime  Offline
Joined: Mar 2008
Posts: 5,840
South Florida
It lubricates the bearings in the water pump. Those "lubricants" wear out over time. The PH level, or acidity, also changes over time, so you want to get the old stuff out and replace so it doesn't corrode.


17 Chrysler Pacifica Mobil 1 5W30
13 Yamaha XT250 Valv MC 10W40
12 Suzuki S40 Rotella 15W40
10 Acura TSX 2.4 PZL Plat 5W30
06 GMC Sierra Nextgen 10W30


Re: Why does radiator coolant need to be replaced? [Re: bubbatime] #4243822
11/07/16 12:12 PM
11/07/16 12:12 PM
Joined: Dec 2005
Posts: 9,891
Upper Midwest
kschachn Offline
kschachn  Offline
Joined: Dec 2005
Posts: 9,891
Upper Midwest
It doesn't in any of my cars, and I've yet to see one where it does. A water-glycol mix is not a very good lubricant, every time it has migrated past the seal into the bearings it has caused them to fail in short order.

Originally Posted By: bubbatime
It lubricates the bearings in the water pump. Those "lubricants" wear out over time. The PH level, or acidity, also changes over time, so you want to get the old stuff out and replace so it doesn't corrode.


1994 BMW 530i, 228K
1996 Honda Accord, 263K
1999 Toyota Sienna, 400K
2000 Toyota ECHO, 271K
Re: Why does radiator coolant need to be replaced? [Re: bubbatime] #4243835
11/07/16 12:26 PM
11/07/16 12:26 PM
Joined: Sep 2015
Posts: 3,861
Connecticut
69GTX Offline
69GTX  Offline
Joined: Sep 2015
Posts: 3,861
Connecticut
Originally Posted By: bubbatime
It lubricates the bearings in the water pump. Those "lubricants" wear out over time. The PH level, or acidity, also changes over time, so you want to get the old stuff out and replace so it doesn't corrode.


With the advent of mechanical seals in water pumps I thought that "lubricating" seals/bearings was no longer applicable.


----------------

2001 Lincoln Cont 4.6L DOHC/ 39K mi / QS HM 5w30 / FUG XG2
1999 Camaro SS M6 /19K /Mobil 1 0w40 /Fram UG /GM MTL-ATF
1969 Ply GTX/RRs
Re: Why does radiator coolant need to be replaced? [Re: veryHeavy] #4243894
11/07/16 01:24 PM
11/07/16 01:24 PM
Joined: Aug 2011
Posts: 9,560
Boston, MA
HerrStig Offline
HerrStig  Offline
Joined: Aug 2011
Posts: 9,560
Boston, MA
Originally Posted By: veryHeavy
My car passed 60,000 which means I need to flush the coolant.
But why?
It still looks nice & green. It feels like I should be able to run to 120,000 since the radiator still continues to keep the engine from overheating. What exactly happens to coolant that it requires replacement after 60000 miles of usage?
Anyone who waits until the engine is overheating to change coolant is crazy. You you wait until your tires blow out before you change them/

Re: Why does radiator coolant need to be replaced? [Re: veryHeavy] #4243907
11/07/16 01:37 PM
11/07/16 01:37 PM
Joined: Mar 2004
Posts: 20,755
Upstate NY
Donald Offline
Donald  Offline
Joined: Mar 2004
Posts: 20,755
Upstate NY
Originally Posted By: veryHeavy
My car passed 60,000 which means I need to flush the coolant.
But why?
It still looks nice & green. It feels like I should be able to run to 120,000 since the radiator still continues to keep the engine from overheating. What exactly happens to coolant that it requires replacement after 60000 miles of usage?


Drain and refill. No need for a flush if things look good. The additives wear out. Drain and refill is cheap compared to parts replacement.

Use the proper coolant and distilled water.

Last edited by Donald; 11/07/16 01:38 PM.

2015 Subaru Forester 2.5 engine/CVT
2015 Ford F250 w/Powerstroke
2016 Subaru Crosstrek CVT (wife's)
Re: Why does radiator coolant need to be replaced? [Re: veryHeavy] #4243915
11/07/16 01:44 PM
11/07/16 01:44 PM
Joined: Jan 2004
Posts: 4,146
California
nthach Offline
nthach  Offline
Joined: Jan 2004
Posts: 4,146
California
The add pack in coolant(mostly corrosion inhibitors) breaks down after a while - more so with conventional green coolant than the OAT(Dex-Cool) and hOAT(Japanese coolants with phosphates, silicated hOAT like G-05/G-40/G-48) coolants used by the OEMs these days.

In rare cases does glycol break down to glycolate - and game over if that does.

Last edited by nthach; 11/07/16 01:44 PM.
Re: Why does radiator coolant need to be replaced? [Re: bubbatime] #4243962
11/07/16 02:37 PM
11/07/16 02:37 PM
Joined: Jun 2003
Posts: 17,348
Deplorable in apple valley, ca
Chris142 Online content
Chris142  Online Content
Joined: Jun 2003
Posts: 17,348
Deplorable in apple valley, ca
Originally Posted By: bubbatime
It lubricates the bearings in the water pump. Those "lubricants" wear out over time. The PH level, or acidity, also changes over time, so you want to get the old stuff out and replace so it doesn't corrode.
any pump made after 193somthething has sealed bearings.. it's the anti corrosion and pH that gets bad.

Last edited by Chris142; 11/07/16 02:37 PM.

02 Wrangler durablend 10w40
87 F250 traveler 15w40
04 Tahoe super-s 10w30
Z400 castrol T 10w40
Can am maveric edge 5w40
57 case tractor 15w40
Re: Why does radiator coolant need to be replaced? [Re: bubbatime] #4243966
11/07/16 02:45 PM
11/07/16 02:45 PM
Joined: Feb 2008
Posts: 6,367
Midwest
Pop_Rivit Offline
Pop_Rivit  Offline
Joined: Feb 2008
Posts: 6,367
Midwest
Originally Posted By: bubbatime
It lubricates the bearings in the water pump. Those "lubricants" wear out over time.


You shouldn't repeat everything you hear at Jiffy Lube.

Re: Why does radiator coolant need to be replaced? [Re: veryHeavy] #4243977
11/07/16 03:04 PM
11/07/16 03:04 PM
Joined: Dec 2006
Posts: 7,641
Toronto, Canada
KrisZ Offline
KrisZ  Offline
Joined: Dec 2006
Posts: 7,641
Toronto, Canada
Water pump or bearing lubrication is nonsense and it has been nonsense for a long, long time in automotive world.

As any automotive fluid, coolant oxidizes, depletes its additives, changes its optimal PH level and simply put, deteriorates through chemical and electrolytic reactions.


2015 Dodge Grand Caravan-27k miles.
2006 Mazda 3-163k miles
Re: Why does radiator coolant need to be replaced? [Re: veryHeavy] #4243978
11/07/16 03:04 PM
11/07/16 03:04 PM
Joined: Jun 2015
Posts: 657
Arizona
Kawiguy454 Offline
Kawiguy454  Offline
Joined: Jun 2015
Posts: 657
Arizona
...Any lubricating needed is just the seal itself. Water pumps have mechanical seal and the water keeps them cool. Anyone that thinks water ever lubricates bearings should think twice

Re: Why does radiator coolant need to be replaced? [Re: Kawiguy454] #4244262
11/07/16 11:37 PM
11/07/16 11:37 PM
Joined: Mar 2016
Posts: 1,351
toronto
PeterPolyol Offline
PeterPolyol  Offline
Joined: Mar 2016
Posts: 1,351
toronto
Originally Posted By: Kawiguy454
...Any lubricating needed is just the seal itself. Water pumps have mechanical seal and the water keeps them cool. Anyone that thinks water ever lubricates bearings should think twice

Definitely. It's just the seal, which is why I don't like to spin pumps dry, even briefly. The seals are spring loaded too, so it's not hard to imagine how being dry or bathed in precipitated-silicate and insoluble-contaminated coolant can wear out a rubber seal that's spring loaded against a housing. The glycol does indeed provide some lubrication to the seal, but conversely the glycol itself never "wears out".

Re: Why does radiator coolant need to be replaced? [Re: veryHeavy] #4244306
11/08/16 03:13 AM
11/08/16 03:13 AM
Joined: Jun 2014
Posts: 2,443
Phoenix, Arizona - USA
SirTanon Offline
SirTanon  Offline
Joined: Jun 2014
Posts: 2,443
Phoenix, Arizona - USA
Instead of second guessing the recommendation to drain and fill your coolant, ask yourself this:

Is it worth the extra (approximately) $20 I would spend on the coolant (and pennies for the water) to safeguard my engine from potential failure or damage resulting from NOT changing out the coolant at the recommended interval?


In my mind, spending $20 or so for the coolant and an hour or two to drain and fill in my driveway - ONCE per 60,000 miles - is WELL worth it.


2010 Ford Fusion SE - 2.5 liter/6F35 Trans - 261,000mi
2014 Nissan Altima SL - 2.5 liter/CVT - 56,000mi
Re: Why does radiator coolant need to be replaced? [Re: veryHeavy] #4244483
11/08/16 10:41 AM
11/08/16 10:41 AM
Joined: Nov 2016
Posts: 479
MN, CA
veryHeavy Offline OP
veryHeavy  Offline OP
Joined: Nov 2016
Posts: 479
MN, CA
I recently topped-off the radiator with fresh coolant. Hopefully that will hold me until my 70,000 mile oil change. The dealer charges $150 for radiator flush.

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