CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Diluted Coolant

I took my car to get serviced at the dealership because it is still under warranty. It has 34,645 miles. While I’m waiting for my car, the service manager came out and told me that my coolant was “corrupted”, that I needed it flushed and that it would cost me $150.00 to do. I chose not to do it because I felt that he wasn’t being completely honest with me. When I got the paperwork for the service, it says that they “found coolant to be diluted”. It seems to me that “corrupted” and “diluted” are two very different things. So, I have two question: 1) Wouldn’t coolant flushing and replacement be a regular maintenance issue and, therefore, should’nt it be covered by the warranty? 2) What does “corrupted” coolant mean vs. “diluted” coolant?

Corrupted…vague generic term meaning it’s not what it should be.
Diluted…more precice as to what exactly is corrupted about it.

Depending on available capacity, full strength coolant could be added to make the mixture strong enough. A cheap hydrometer can be purchased at any parts store so that you can chech the strenght of your coolant.

Generally coolant is a concentrate and mixed at 1/2 coolant and 1/2 water.
Diluted means you have too much water for coolant ratio.

Whether called for in the owners manual or not, I’d be inclined to replace my coolant with factory coolant at 35,000 miles. Just a drain and fill, no flush needed if replacing it with identical coolant. An independent shop can handle this.

As for ‘corrupted/diluted’ - anybody add water to your system? Maybe thought they were refilling the wiper fluid? That’s the only way for coolant to be diluted.

I’m not sure how much we can help. “Corrupted” isn’t a term usually used with coolant. Perhaps they meant “contaminated”. On the other hand, “diluted” would probably just mean the wrong mix of coolant to water. However, these are two totally different issues. You really need to go back to them to get a clear explanation, unless you want to get a second opinion from a different mechanic.

Also, when does your owner’s manual call for the coolant to be replaced?

  1. Wouldn’t coolant flushing and replacement be a regular maintenance issue
    Yes, it is periodic MAINTENANCE.

and, therefore, should’nt it be covered by the warranty?
No. The warranty covers defects in material or workmanship not maintenance items. Tires, brakes, fluids etc, those are things you’re supposed to be maintaining.

How old is your car? It’s probably time for a coolant change, but any repair shop can perform that service for considerably less…Anti-freeze ability to protect against freezing lasts forever…This protection level can be tested is a minute or less with a simple tester. What degrades is it’s ability to protect against corrosion in the cooling system…Deposits start to form which can plug up your radiator and heater core…

Corrupted means that it is not working, but I have not seen that term used before when referring to coolant. contaminated means that there is something in there that is not supposed to be in there, like oil or transmission fluid. Diluted just means that it is not at the proper ratio of antifreeze to water.

First, you need to look in your owners manual and see what the maintenance interval is on the coolant. There will be years or miles, i.e 3 years or 50,000 which ever comes first. If your coolant is older than the recommended in the owners manual, either in time or miles, then you need to get it replaced, this does NOT mean it has to be flushed.

Next, you need to determine if it is contaminated, “corrupted” or diluted. If you are comfortable with this, get a coolant tester at a car parts store or the automotive section of a discount store. The cheap ($1) tester with the little balls is good enough for this purpose.

With the engine cold, open the hood, remove the radiator cap and suck a little fluid up into the tester. You can also get a sample from the overflow tank if you have to, but I prefer to get one from the radiator, but not all radiators have a cap now. The directions on the package the tester came in will tell you the antifreeze:water ratio by the number of floating balls.

Look through the glass tube at the coolant. If there is an oily substance floating in it, then you need to take it to a mechanic and find out why it is there. If the coolant is brown, like muddy water, then it is used up and no longer providing corrosion protection, it must be changed immediately. If it is cloudy or milky, then it needs to be replaced soon.

If it is a clear color, like yellow or red, but clear, then it is still good. If it doesn’t have the correct number of balls floating, then you need to get the factory spec antifreeze, full strength, and drain some of the old coolant out and replace with the new.

If it is close to full strength, that is one ball short of the correct mixture and yo are close to the change interval, then just go ahead and have it changed, but not flushed, just drain and refill. I would not use the dealer for this because it is clear that he has bought a flush machine and he needs to flush as many coolant systems as he can to amortize the cost of the machine over as many cars as possible in order to make money.

Find a small independent shop with a good reputation and start taking the car there for all its service. A good independent mechanic should be willing to review the maintenance schedule in your owners manual and explain the need for each service and help you get on a schedule that should result in the lowest total owner cost for you for this vehicle. Only use the dealer for warrantee work.

“the service manager came out and told me…”

There’s the heart of the problem.
They know surprisingly little about cars.
How do you tell they’re making stuff up?
When their lips are moving!

I agree with circuitsmith above. A service manager’s job description includes scaring car owners into agreeing to additional services. It is quite likely the mechanic never even inspected your coolant.

That said, I also agree with other posters who recommend coolant replacement at this point based simply on mileage and age of the car. A simple drain and refill will do, not an expensive flush. No, it is not covered by warranty. The procedure is so simple you might even do it yourself in your driveway.

If you do it yourself, just remember that it is very toxic so keep your pets out of it. One or two laps and your pet will die.

If you live in an area where freezing temperature are common, verifying that the existing coolant meets the needed freeze protection for your area needs to be done immediately. Otherwise you might get an unexpectedly cold Feb night and could incur very expensive engine damage if the coolant freezes. Until that is done, keep the car parked in a place that doesn’t get below 32 deg F.

I’m not sure what the tech meant by “corrupted”. I’ve never heard that term applied to coolant. I expect they measured the specific gravity, and it isn’t what it should be, a 50/50 mix. Someone at some point may have added plain water to the coolant, which diluted it. Have you ever had any cooling system component worked on? Like a leaky radiator, etc? In any event, any inde shop can drain the old coolant out and put in new. I don’t know how much they’d charge, but I expect it should be less than $150 anyway.

If you live in an area where freezing temperature are common, verifying that the existing coolant meets the needed freeze protection for your area needs to be done immediately.

Coolant is not just used for freeze protection…it’s also used to help prevent boiling over. A 50/50 solution is ideal for both and should be used no matter where you live.

I agree with the others who have suggested that–at the very least–you have the coolant’s level of protection checked (and corrected, if necessary) in order to avoid both freeze-ups and overheating. Personally, after 35k miles I would flush the cooling system and install fresh coolant in the proper 50/50 mix with water.

That being said, I would also suggest that the OP take the time to read the terms of the warranty, because her statement (“Wouldn’t coolant flushing and replacement be a regular maintenance issue and, therefore, should’nt it be covered by the warranty?”) indicates a total misunderstanding of what a warranty covers. The warranty booklet, along with the Owner’s Manual and the maintenance schedule, should be sitting in the glove compartment. It would be really helpful to the OP if she read all of these booklets.