Coolant level when cold

[Will2]

Oh boy... low coolant on my '25 GT after ~9K miles. Had the same issue on my '24 Ecoboost (which had a coolant leak from the factory). I traded in that car for the GT due to the many quality defects, but my '25 GT is apparently no better.

Other people having this? I never fiddled with the tank cap, no obvious signs of leak anywhere, no white exhaust/burning coolant. I took photos when the car was brand new and coolant was not low then, so it got consumed/leaked in the meantime. Either this is a systemic issue with S650 Mustangs, or perhaps my driving style is magically making coolant disappear.

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[MustangNoob]

same here. just top it off when cold and monitor. Mine also change color at about 4k miles. See thread https://www.mustang7g.com/forums/threads/coolant-consumption.171188/

It came low from the factory but never had any heat issues

 

[Starship Enterprise]

I don't understand the coolant looking like dirty dishwater. I have read somewhere that coolant getting darker with use is "normal" but still...

I don't have a ton of miles on my car, but it's still bright green/gold.

 

[Katzenjammer]

I just went through a "slightly low coolant when cold" situation on my 2024 GT in the last month. The car was manufactured in Feb 2024 and bought in May 2024.

In mid-November 2025 I noticed it for the first time; don't know how long it was like that, as I may not have checked it when completely cold, especially with the weather here in southern AZ. There never has been a sign of a leak or foggy exhaust.

I immediately took it into the Ford shop and they topped it off and told me to watch it for signs of the level dropping. It was a little low yet when cold, since they guessed how much to add when it was still warm, but it has been unchanged for a month.

I bought the correct Motorcraft premix per the owner's manual and added the small amount needed to reach minimum when cold, and it's now holding that level.

The manual on p.303 says:
If you have to add more than 1.1 qt (1 L) of
engine coolant per month, have your
vehicle checked as soon as possible. (!!!)

Personally, I can't believe there is any normal situation where the coolant level drops significantly. The interwebs says (not referencing any specific car) there can be a little loss over many months especially in hot weather, "due to overflow or evaporation from the reservoir, which is vented." I find this hard to believe unless the pressure exceeds the relief pressure of the reservoir cap in extreme cases.

I can't recall seeing a drop of coolant level in any car I ever owned.
Anyone know if it's common for the cap to actually vent at times on the GT?

 

[Zig]

I just went through a "slightly low coolant when cold" situation on my 2024 GT in the last month. The car was manufactured in Feb 2024 and bought in May 2024.

In mid-November 2025 I noticed it for the first time; don't know how long it was like that, as I may not have checked it when completely cold, especially with the weather here in southern AZ. There never has been a sign of a leak or foggy exhaust.

I immediately took it into the Ford shop and they topped it off and told me to watch it for signs of the level dropping. It was a little low yet when cold, since they guessed how much to add when it was still warm, but it has been unchanged for a month.

I bought the correct Motorcraft premix per the owner's manual and added the small amount needed to reach minimum when cold, and it's now holding that level.

The manual on p.303 says:
If you have to add more than 1.1 qt (1 L) of
engine coolant per month, have your
vehicle checked as soon as possible. (!!!)

Personally, I can't believe there is any normal situation where the coolant level drops significantly. The interwebs says (not referencing any specific car) there can be a little loss over many months especially in hot weather, "due to overflow or evaporation from the reservoir, which is vented." I find this hard to believe unless the pressure exceeds the relief pressure of the reservoir cap in extreme cases.

I can't recall seeing a drop of coolant level in any car I ever owned.
Anyone know if it's common for the cap to actually vent at times on the GT?

Is it confirmed if the factory burps at fill?

 

[Junkyard Dog]

Are you guys getting a check engine light or some sort of dashboard warning regarding low coolant level, of are you just noticing the reservoir is low?

 

[Katzenjammer]

No trouble lights, only noticed the level was low when cold.
It has not dropped since bringing it up to minimum when cold.

 

[Frogdog1]

Mine came a little low from the factory. Just had them fill it properly.

 

[TheACN]

Mine came at almost—low mark from the factory, then this is where it is after 2500 miles. I bought the Motorcraft pre diluted yellow coolant from amazon, will top it off when it comes out of its cocoon.

 

[Katzenjammer]

Mine came at almost—low mark from the factory, then this is where it is after 2500 miles. I bought the Motorcraft pre diluted yellow coolant from amazon, will top it off when it comes out of its cocoon.

This is where mine was, and to update, it is still at the min mark when cold since I topped it off.
So, this is looking more and more like it's because it's not burped at the factory.

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