I bought a used motorhome that is 8 years old. I have no reason to believe the previous owner ever changed out the Dex-cool coolant. The motorhome has only 14,500 miles on it. I read Dex-cool is good for 5 years. Should I have the whole system flushed and refilled? Or should I just drain and refill the radiator? Alternatively, since the stuff is still a nice color, is there an additive I can put in to "restore" it, such as rust inhibitor or something?
Dex-cool over aged, low miles, change out?
- Thread starter TallPaul
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If you have the pressurized reservoir. I might be tempted to just replace it in kind. But if its the non-pressurized reservori type I would do a thorough flush and go with say SuperTech extended life stuff.
I don't claim to be an expert but having had problems with using Dex on a non pressurized reservoir, I have tried to listen to the experts on here. That's what I base my actions on.
I don't claim to be an expert but having had problems with using Dex on a non pressurized reservoir, I have tried to listen to the experts on here. That's what I base my actions on.
The reservoir, you mean the overflow tank? It's a plastic tank. Nothing pressurized about it. Cap just snaps on. So there is an extended life Dex-cool. Well, okay, I will take it in this summer for a complete flush abnd refill.
I have yet to see a coolant "expert" on these boards. What I can tell you from my extensive (but non-"expert") experience with Dexcool is that after 8 years, regardless of mileage, you'll be LUCKY if the cooling system isn't already thoroghly sludged. I'd strongly reccomend a complete flush. Refilling with Dexcool is fine- but from what I've seen, I would never consider it a "long-life" coolant. I think it'll give good corrosion protection if drained & filled every two years. I wouldn't run it longer than that. I know that lots of people routinely leave that evil stuff in for 5 years or more with good results... but I've also personally had the displeasure trying to flush the crud out of several Dexcool systems that were little older.
Any details on this motorhome? What sort of chassis/engine is it?
Any details on this motorhome? What sort of chassis/engine is it?
^^ didn't have any problems with flushing the 6 year old stuff out of my gfs 01 cavalier (pressurized resevoir). Had just under 98,000 miles when I changed it out. Still was orange, smelled like it should, and I found no brown sludge or anything in the coolant. Must be one of the lucky ones
Motorhome is a '99 Chevy one ton van chassis with a 454 V8. Only thing I know about Dexcool is I had heard some horror stories. Hope mine isn't one of them. As I say, the fluid looks pretty good in the reservoir, but yes I will get the system completely flushed.
Is is possible or worthshile to go over to standard coolant on the refill?
Is is possible or worthshile to go over to standard coolant on the refill?
I would get the Dexcool out as soon as possible. From what I understand the DexCool reacts with air in a system where you just have the unpressurized overflow. You can just go with the standard stuff. I would stay away from Dex and Dex clones.
I have mixed feelings about Dexcool. Both of my GM cars came with the stuff- and, based on my multiple bad experiences with it, I immediately flushed the stuff out. Both have run fine for years with low silicate green antifreeze (John Deere brand, at the moment). If you do decide to rid yourself of this nasty orange substance, be sure to do a thorough flush.
Also, I worked at a Cummins dealership for several years in the mid-late 90's. I changed DOZENS of head gaskets on N14 engines- paid for by the Texaco warranty. Dexcool made the seals swell and leak. We were told that Texaco had changed the formulation to address this problem, and (as stupid as I thought this was) we refilled those engines with the new improved Dexcool. To be fair- those engines never came back... so I think it's safe to assume that the problem was taken care of.
I've been reconsidering of late, though- partly based on what I've read on this site, and partly based on my experience with Dexcool. While I have dealt with lots of particularly nasty sludge in Dexcool systems, it was -without exception- in systems that had very likely never been flushed for 5 years or more. In the engines that I've disassembled that were relatively new (all diesels,
Potential bennefits:
*Possibly better corrosion protection (under ideal conditions)
*possibly better heat transfer (so I'm told).
Potential risks:
*Rumored gasket problems (I doubt it's an issue nowadays)
*Very common, pervasive, and nasty sludge when run under less than ideal conditions OR for even slightly longer than the reccommended 5-year service life.
Also, I worked at a Cummins dealership for several years in the mid-late 90's. I changed DOZENS of head gaskets on N14 engines- paid for by the Texaco warranty. Dexcool made the seals swell and leak. We were told that Texaco had changed the formulation to address this problem, and (as stupid as I thought this was) we refilled those engines with the new improved Dexcool. To be fair- those engines never came back... so I think it's safe to assume that the problem was taken care of.
I've been reconsidering of late, though- partly based on what I've read on this site, and partly based on my experience with Dexcool. While I have dealt with lots of particularly nasty sludge in Dexcool systems, it was -without exception- in systems that had very likely never been flushed for 5 years or more. In the engines that I've disassembled that were relatively new (all diesels,
Potential bennefits:
*Possibly better corrosion protection (under ideal conditions)
*possibly better heat transfer (so I'm told).
Potential risks:
*Rumored gasket problems (I doubt it's an issue nowadays)
*Very common, pervasive, and nasty sludge when run under less than ideal conditions OR for even slightly longer than the reccommended 5-year service life.
Manual says the Dexcool is good for 5 years or 100,000 miles. Since I have only 15,000 miles I am thinking the 8 years is not so critical, i.e., there is no problem yet. Still, would be good to change out.
Low miles but the time will take it's toll.
I sort of agree, but if the DexCool by its nature causes gaskets to leak...Can you see where I am going here.
Dexcool does not cause gaskets to leak. The gasket problem was with the 3.1 and 3.4 V6s (reference) .
Seems if the gasket leaks, then oil will get into the coolant which would cause the sludgy mess.
I only hope the bad gasket design was not used on the 454 V8.
Seems if the gasket leaks, then oil will get into the coolant which would cause the sludgy mess.
I only hope the bad gasket design was not used on the 454 V8.
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^^ didn't have any problems with flushing the 6 year old stuff out of my gfs 01 cavalier (pressurized resevoir). Had just under 98,000 miles when I changed it out. Still was orange, smelled like it should, and I found no brown sludge or anything in the coolant. Must be one of the lucky ones
same here with the 96 sunfire. 6 yrs/45k miles on it.
Well I drained it out last night. Got 23 quarts of nice clean, clear red Dexcool/water mix. There was a little sediment that came out the engine block drains. The sediment was metal like left over debris from casting. No more than a half a thimblefull I'd say. Shiny metal, not a hint of rust. Guess this engine is clean as a whistle inside. Now I have to refill it. Will pull a heater hose to relieve the upside, so air pressure doesn't build up until the thermostat opens and cause a blow of coolant out the rad neck. I assume the heater hose that connects to the water pump is the one that will be flowing toward the heater core, and the other line is the return, right?
In addition all the "GM Cooland Tabs" that get put in these engines add to the sludge, or perhaps is the source of all the sludge. I hope you're right that the 454 did not have an issue, I don't know. The 5.7L (350's) of that time frame did have gasket problems (personal experience with a '97 and '99).
Glad to hear it all came out clean.
JHZR2
Staff member
keyword "or". Youve surpassed one of the two criteria, and there is a reason why they are both put in with an 'or' qualifier.
Change it, at least drain the radiator and refill and repeat this a couple times over the summer.
JMH
Change it, at least drain the radiator and refill and repeat this a couple times over the summer.
JMH
This is probably politically incorrect on this forum, but I was told by a GM engineer who currently designs engines for GM and worked on the DexCool project originally that DexCool, theoretically, should last much longer than five years since it does not contain any sacrificial components such as silicates and/or phosphates.
Many of the DexCool problems (sludge, etc) can be traced back to less than perfect cooling systems. Sure, I agree that DexCool is more vulnerable to such problems compared to the coolants of yesteryear, but there is no reason why DexCool would cause problems when used in the right application provided that the system is in perfect or near perfect condition.
Heck, I put Prestone All Makes All Models in my dad's '92 Previa last Dec (arguably, this stuff is DexCool in a different bottle) and I have had no issues either. Ditto for a '96 Saturn that originally warned AGAINST using DexCool. I've used DexCool or the equivalent in that one for more than three years now without any problems.
Many of the DexCool problems (sludge, etc) can be traced back to less than perfect cooling systems. Sure, I agree that DexCool is more vulnerable to such problems compared to the coolants of yesteryear, but there is no reason why DexCool would cause problems when used in the right application provided that the system is in perfect or near perfect condition.
Heck, I put Prestone All Makes All Models in my dad's '92 Previa last Dec (arguably, this stuff is DexCool in a different bottle) and I have had no issues either. Ditto for a '96 Saturn that originally warned AGAINST using DexCool. I've used DexCool or the equivalent in that one for more than three years now without any problems.
Do you have some reference material to validate this statement?
rriddle3, Google GM Coolant Tabs" and you may find some info. If I read it right, the coolant tabs are supposedly to fix the bad design gaskets from inside, but didn't work so well. Also, it may be that there are issues when mixing iron block with aluminum heads, but pretty sure my engine is all iron.
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