How much coolant loss is normal?

[ExYukon]

I have a 2023 Silverado with the 6.2.  It has 29K miles on it.  In June, I noticed the coolant level in the overflow tank was a bit low, like a quarter or a third of an inch down.  I topped it off then.  Today it is again down about a quarter of an inch.  I'm checking the level when the engine is cold, of course.  Is that normal/OK?

 

I once had a Subaru that also seemed to need semi-regular topping off, but I also noticed on that car, once the level in the tank was down about half an inch, it did not drop further.  Should I leave me truck as-is for now and keep watching it, or top it off again?

[PunchT37]

It is called an expansion tank. So, it will "breathe" with temp. Let it be for now and watch it.

[Byrds8]

Going to have mine looked at next week for this. Under 35K miles and filled it up to the top of the book in March. Today it's down about an inch. That was roughly over 7K miles. I dont think it should be using this much coolant. However, there is no smell in the engine bay or out the pipes and nothing it the oil.

[johnnyquick]

My 2020 has the ever so slightest leak in a radiator seam that was undetectable until I had the fender well liners out and was crawling around under it when doing the trans fluid and filter.

Passenger side bottom corner.

Never any wierdness or crash etc.

It has 64k on it now and has used a little here and there for a couple years.

These trucks are horrible quality IMO

Edited October 21, 2025 by johnnyquick

[Black02Silverado]

There shouldn't be any loss.  In all my vehicles over the years, I never had one that I had to add coolant.  Just be sure to check it at the same time every day, like first thing in the morning before you take it out to drive.

[Grumpy Bear]

Mine has used a bit a year since new. Now 191,300 miles. Never see a leak. It isn't much and if it is leaking I'll not find it at this rate of loss. Holds a standard pressure test with ease. I'm not randomly swapping parts to chase it. 

 

I read from a supplier of silicon radiator hoses that all hoses are 'permeable'. Silicon more so than factory but all are permeable. 

[Gangly]

I have had to add a little coolant every 30k - 40K miles since new.  I will get a waterfall/gurgling sound behind the dash when it gets a little lower than full (nowhere near the low indicator on the tank), so I add enough coolant to get a little above the "high" indicator, and the sounds go away for another 30k - 40k miles.

[KillerKilgore]

Buy or rent a radiator pressure tester. Follow directions. Could also be a cap that isn't holding pressure. Causing the tank to overflow a little when hot. But it is a closed system and should not have to be topped off unless there is an issue somewhere.

 

They also make exhaust gas test fluid. Changes color if exhaust gas is present in coolant. A little goes a long way.

 

[tjonesdfw]

Been down this road before too and seems it repeats itself every 12 months or so.  The first time the dealer pressure tested it twice... the first time it leaked down, and the second time it held, so they just topped it off and sent me on my way.  Sending it back to the dealer this week for them to do the same since I'm under an extended warranty, but its down about an inch again and the waterfall sound in the dash at startup is back.  Every time I stop and get out, you can smell antifreeze around the front end, but there's no visible signs of a leak.