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How often do you top off your coolant?


Obsessed Member
I have a 2004 Toyota Corolla and I have to fill the reservoir around every 6 months or so from completely empty to full. I always thought I have a leak somewhere, but I've never been able to find it. I just chalked it up to evaporation.


What, me conspiracy?
Yep, you got a leak. Coolant never needs topping off unless you have a leak. This could be external, or it could be internal, with the engine consuming it.

I assume this is a CE or S with a 1.8L?

Look for residue all around under the hood. On and near all the hoses and their connections, on the radiator, etc.. look around carefully with a flashlight, look for wet spots or spots that look like they have been wet recently. A small leak of that size at a radiator tank seam or elsewhere won't necessarily leave a spot on the ground.

Usually small external leaks you will get whiffs of on occasion. Especially when sitting in drive-thrus, as you're creeping along, it's usually hot, and your window is open at least part of the time.
Good title for a beer drinkers forum as well:)

"Can I pour you a beer, Mr. Peterson?"
\-"A little early isn't it, Woody?"

\-"For a beer?"

\-"No, for stupid questions."

If the Coronavirus really isn't about a beer...
Then why do I keep seeing cases of it?

yes, could be a leak

Typically, coolant loss is caused by a leak. A leak can be either internal, such as a leaky gasket, or external, such as a hose failure or crack in the radiator. An external leak is usually determined by a puddle of coolant underneath the vehicle. Coolant loss can also be caused by a leaky or improperly sealed radiator cap allowing the super-heated coolant to evaporate.

All jokes aside,
good luck with the issue
I had a good radiator mechanic
but since this bs
he has headed out of this insanity


Geth Prime
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I've used Wally's on and off over the years since ~1990. They had a rough patch or two, but they are on top of their game now. Highly recommended.
Wallys huh I think u have recommended them before I might have to take my 4 runner there for tranny fluid change break fluid change and coolint change only have 60000 miles on it but
I would fell better


Staff member
Get a cheap pressure tester. Find on on Amazon or HF. Like before check for build up at connections, or the water pump, check in the footwells if so then heatercore. Also check your engine oil, if it is milky... head gasket or head.


Obsessed Member
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I think it’s mileage dependent, if I’m running all over the uzi triangle I may use about a cup. In general about a gallon per year for both vehicles tpopping.


What, me conspiracy?
I was just about to ask if antifreeze shows up under UV light. Might not even need to put in a dye.
Don't think it does, no. But honestly, if you need dye to find a coolant leak, you're probably just not looking hard enough. Even a small amount of coolant leaking leaves residue, and if you're continuously losing a small amount as described here, there will absolutely be residue and corrosion around wherever that leak is.


Hydrostatic shock creator
My reservoir I top off a few times a year as they will evaporate a bit but the radiator itself should not be losing coolant at all. Majority of the leaks come from a bad radiator cap. Check the rubber seal on it.


Obsessed Member
Half the people I know say I gotta top it off a few times a year because the distilled water evaporates through a vent tube, the other half says I have a leak because they never have to top off their coolant


What, me conspiracy?
Half the people I know say I gotta top it off a few times a year because the distilled water evaporates through a vent tube, the other half says I have a leak because they never have to top off their coolant
If your system is properly sealed, with a good radiator cap, and a proper mixture of clean 50/50 antifreeze, you should not be losing any appreciable amount of coolant through evaporation. A proper mixture of antifreeze evaporates very, very slowly, and on a properly maintained and sealed system, the only avenue for evaporation would be the small vent for the reservoir. It's very unlikely that you're losing the contents of that reservoir to evaporation every six months.