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Discussion Starter · #1 ·
Noticed today on my bi-weekly routine oil/fluid check that the coolant reservoir is below the normal but above the low line. I'd estimate it's about half way.

I don't know how long it's been like that. Haven't seen any red temp indicators or anything yet.

Should I just go grab some Subaru Super and top off the reservoir? Anything else to look for first?

I don't see any coolant under the hood on hoses and nothing on the driveway. Putting cardboard under it tonight to be safe. Does coolant just evaporate over time?

(Have 79k on it, car was purchased April 2011, so it's 6 years old...)
 

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2002 3.0 VDC Wag + 2018 2.5 Leg Ltd
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open the cold rad neck and check.

and top off,...cars loose a little over long periods of time,
not a big deal to add 16 oz every once in a while to the overflow bottle just to bring it back to the fill line.

______

I don't know how 2010-12 owners feel, but I would think it is a good thing to replace the OEM rad cap and OEM thermostat after six years.
(I think I would be out to change them, and maybe put the used blue coolant mix back in).

@brucep or @KansasMatthew might have thoughts.
 
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Peek at it weekly for awhile! I would need to set my phone to remind me- I only check monthly by habit.
 

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No Worries!! Check coolant on COLD engine... as long as level in reservoir is above the low mark, all is well. If you need to add to your 2011... use only ASIAN BLUE antifreeze.

Checking the level under any other condition will result in imprecise measurement..... as the engine heats up, the level goes up. There is no way to predict beyond that.

It is not recommended to actually open the cooling system by removing the radiator cap. This introduces air into the system which can take weeks to fully purge out.
 

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No Worries!! Check coolant on COLD engine... as long as level in reservoir is above the low mark, all is well. If you need to add to your 2011... use only ASIAN BLUE antifreeze.

Checking the level under any other condition will result in imprecise measurement..... as the engine heats up, the level goes up. There is no way to predict beyond that.

It is not recommended to actually open the cooling system by removing the radiator cap. This introduces air into the system which can take weeks to fully purge out.
what do you think about replacing the rad cap, and thermostat as a maint. item? (before the 11 years of life expectancy of the OEM subaru super blue fluid).
 

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what do you think about replacing the rad cap, and thermostat as a maint. item? (before the 11 years of life expectancy of the OEM subaru super blue fluid).
(You asked.....)

Personally, I am a believer in "If it aint broke - dont fix it".... but this is a personal choice and also depends on expected reliability.

I know how the various automotive systems operate and can determine how far I can push things before mandatory replacement is indicated.

Also, I STRONGLY believe that "New does not mean GOOD". All too often, I have seen brand-new, out of the box parts fail within a month. This is especially true with the "made in China as cheeply as possible" of many autoparts.

I arrived at these beliefs after over 45 years maintaining all manner of electro-mechanical devices. All too often, I have seen that the very action of taking something apart to replace a functional component may introduce some other type of failure.

Do not get me wrong, I am a big believer in replacing fluids, filters and performing other PMs (Preventative Maintenance) Ignoring a machine is asking for failure.

To more specificcly answer your question regarding Cap and Thermostat....

I have NEVER seen a pressure-vacuum cap fail if the antifreeze is maintained properly.

I have seen exactly TWO separate incidents of thermostat-failure... in both cases the vehicle was drivable enough (gently) to get it to service.
 

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Back in 2006, SOA issued a TSB about the radiator cap. In essence, it calls for the cap to be inspected and washed to ensure there are no particles attached to the rubber seals.

If the cap leaks because of even a spec on the seal (either the pressure or vacuum side), it will not allow the cooling system to achieve the proper internal pressure. That pressure is needed to raise the boiling point of the coolant, and is particularly relevant to the coolant as it flows by the cylinder walls and through the head. Low pressure can allow some local boiling, and the gas from that will be exhausted through the cap and reservoir. The net effect is a small loss of coolant which becomes apparent when the engine cools and liquid is drawn back from the reservoir.

I check the level my 07's reservoir very frequently. Perhaps on two or three occasions in the past 10 years I've noticed a small noticeable loss (a few mm at most) that repeated over several days. In each instance, I removed and thoroughly cleaned the cap, and didn't see any more loss.

There is good reason to remove and inspect/clean the cap. It should not cause any burping issue. When the cap is removed the level in the rad should be up to the ledge that the cap inner seal is pressed against, and if it's not, it should be topped up to that level. There is no loss from the coolant system when removing the cap. After it's replaced, the air space above the rad neck ledge, and in the (now) empty upper part of the hose going down into the reservoir, will be filled on the next drive cycle.
 

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Discussion Starter · #8 ·
Thanks, all. I'll keep an eye on it, and if it seems to drop any more I'll first try adding some OEM Super Coolant to the overflow reservoir, and if it continues I'll try inspecting/cleaning off the cap.

Much appreciated!
 
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