Anti freeze consumption: How much is allowed?

[LucasDK]

Hi,

Can anyone tell how much anti freeze consumption is allowed in a standard passenger vehicle?

After driving my car approx 60000 miles I lost about 5-10 ounces out of my anti freeze container. Is that normal? From a theoretical point of view I guess it should be 0,0 at all times even after 300000 miles. I don't have anti freeze in the oil.

What is your opinion?

Lucas

 

[joegreen]

Idk but i know some of my high mileage over 200k vehicles need a little coolant every once in a while. my 250k honda accord never seems to lose any coolant.

 

[Puhdantic]

0

 

[demarpaint]

That's a lot of coolant for 6K miles. If you don't have visible leaks I'd pressure test the system, there's a chance the head gasket could be bad, or you have a leak. I had a similar issue with my wife's 08 Liberty. FTR I took me over a year and quite a bit more miles to lose that much coolant, but it did warrant further inspection. Pressure testing and careful inspection indicated the water pump was on its way out.

 

[AJB0009]

That's a lot of coolant for 6K miles. If you don't have visible leaks I'd pressure test the system, there's a chance the head gasket could be bad, or you have a leak. I had a similar issue with my wife's 08 Liberty. FTR I took me over a year and quite a bit more miles to lose that much coolant, but it did warrant further inspection. Pressure testing and careful inspection indicated the water pump was on its way out.

60k miles, not 6k.
~
I have never kept track of amounts, but in my 12 Ford Fusion and 06 Toyota Tacoma, I do notice that the overflow bottle is down a little bit after a year or so.

 

[Lubener]

There should be no consumption. You either have a minor external leak are an internal one where the coolant is getting in the engine.

 

[SC Maintenance]

No system I have ever owned was 100% sealed and evaporates a little over time. A few ounces in 60K miles is likely this. You could have a weak pressure cap or a very small leak somewhere. In addition to a pressure test, it would be worth monitoring your temps via OBD. If its getting hotter than spec it will vent more.

 

[LouC]

In my 07 Jeep 5.7 had a few small leaks over the years one was from the thermostat gasket the other was from the pressure cap which was replaced with a new design.

 

[eljefino]

Your consumption is fine.

IDK if you have a pressurized surge tank or non-pressurized overflow, but when pressure builds up too much the system vents a little steam. If it vents it into a non-pressurized overflow it bubbles through some less-than-boiling coolant. If that doesn't cool it down enough to condense it, it winds up as water vapor in the overflow with some escaping through the vent.

Ironically, the less coolant there is in your overflow bottle, the more you can lose due to less bubble-cooling-time. I like to keep mine full above the full line, leaving only enough airspace that it doesn't puke out.

Many owners manuals mention an allowable amount of consumption. It's not a closed system (that doesn't evaporate) like brake fluid.

 

[atikovi]

Why do you think it's a consumption issue? It could just as well be a displacement issue it there are no leaks, which in and of itself is questionable especially on something with 300000 miles. There might have been trapped air pockets in the system from the last coolant change that worked their way out and got displaced by coolant, thus lowering the coolant level making you think the coolant was somehow disappearing. I know that after doing a coolant change, even with a vacuum filler, it takes a few warmup cycles before the level stops dropping in the overflow bottle.

 

[emmett442]

Sealed system. Mo leaks, no evaporation. Should be zero loss.

 

[SC Maintenance]

Sealed system. Mo leaks, no evaporation. Should be zero loss.

Its not really sealed - is why you have a pressure cap. People think the cap only vents when its over-heated but that is not true - the cap is not air tight, its a simple seal compressed by a spring. In normal operation when you air rises from ambient to 220 it expands a lot, and vents out the cap a very small amount. When the car cools it sucks air back in the same way. Over many cycles you loose coolant from evaporation. How much depends on how you use the car and other factors. OP said 5 - 10 ounces in 60K miles. Less than 2 ounces per 10K miles isn't a small amount, but is still plausible.

 

[zrxkawboy]

Sealed system. Mo leaks, no evaporation. Should be zero loss.

Depends on the vehicle. Many overflow bottles are not sealed, and they see flow in and out with every heat/cool cycle.

 

[joekingcorvette]

Should be zero.

 

[thescreensavers]

Its not really sealed - is why you have a pressure cap. People think the cap only vents when its over-heated but that is not true - the cap is not air tight, its a simple seal compressed by a spring. In normal operation when you air rises from ambient to 220 it expands a lot, and vents out the cap a very small amount. When the car cools it sucks air back in the same way. Over many cycles you loose coolant from evaporation. How much depends on how you use the car and other factors. OP said 5 - 10 ounces in 60K miles. Less than 2 ounces per 10K miles isn't a small amount, but is still plausible.

Sounds like maybe the OP should try a new Cap?

 

[repairman54]

Put the UV dye in to really track any possible seepage. That stuff will detect the tiniest seep.

 

[Gyro Gearloose]

In any vented overflow bottle there will be a small exchange of air in and out of the bottle with each heat cycle if for no reason other than expansion and contraction of the air in the bottle from under hood heat It would be reasonable to expect that the air pushed out out of the bottle would have picked up water vapor from the liquid in the bottle and be near 100% humidity when expelled. And air at under hood temperature can carry way more water vapor than air at room temperature. The replacement air during the cooldown phase would be whatever local humidity was and be relatively "dry" compared to the expelled air. Over time the cycles of evaporation and exchanging the tiny amounts of air would add up.

I also question whether the mechanical seal on any water pump is truly100% impermeable at the molecular level. I know they don't leak liquid but I would not be surprised if a few molecules of vapor don't sneak past them trying to contain boiling hot liquid under pressure while spinning at a couple thousand rpm.

On my cars I check coolant levels but normally don't add coolant between changes. It is fairly typical that they will start out with the overflow bottle filled to the upper mark, but by the time I change coolant 4-5 years later it will have drifted down to the lower mark. 5-10 ounces in 60K miles doesn't sound like cause for alarm in my experience.

 

[Leo99]

I had a bad cap and a lot of anti-freeze evaporated. I think a little top off every 60k miles is acceptable and I wouldn't chase this too much.

 

[Pelican]

Hi,

Can anyone tell how much anti freeze consumption is allowed in a standard passenger vehicle?

After driving my car approx 60000 miles I lost about 5-10 ounces out of my anti freeze container. Is that normal? From a theoretical point of view I guess it should be 0,0 at all times even after 300000 miles. I don't have anti freeze in the oil.

What is your opinion?

Lucas

There should be hardly any consumption between coolant changes assuming you do this every 5 years.
Not a believer of 160K mikes or 10 yrs for coolant.

 

[WeyounDS9]

It also "vents" into the overflow...