Stop Leak or any other coolant sealant? Any actual experience?

Sister's van is acting up, it'll be a couple weeks minimum before her mechanic can get to it so she's looking for something to fix a small leak.  She would just fill it periodically, but she lives in the woods and doesn't want coolant dripping and contaminating the ground.  She's thinking of using Stop Leak

I've never heard any good things about it, but the people I've known that would turn to it are the type to turn to it first and as a permanent fix, not as a stop gap.

Anyone ever actually used it or something along those lines?

In reply to Mr_Asa :

Lessee... 25 years ago I put Barr's in a radiator in my work van. Cuz roadside. That van got retired years ago but not cuz of the radiator leak. Never did get around to actually fixing it, it just sorta.. stopped leaking..

Only thing I've had luck with not plugging a rad and temporarily stopping a leak was the powdered "solder seal" stuff.

I used Barr's on the craptastic 02 explorer my wife had because 1.i hated it and didn't want to work on it totally constantly, so it cut it back to only waking moments working on the crap pile and 2. 4 bucks was all I was willing to put into it

It worked for over a year with no problems

In reply to Antihero :

I've heard good things about Barr's from the few people I know that aren't idiots that have used this stuff. 

Internet seems to like K-Seal ST5501

My Avalanche has the bad head castings that are prone to cracking. They have minor cracks that cause a faint scent of coolant and require topping off the radiator bi weekly.

I dropped a bottle of K-seal in it and haven't had to top off the coolant in.... geeze. Almost a year?

K Seal has worked the couple times I used it. 

Nutmeg and black pepper are my go tos. 

But ive used the barr stuff in a camry with no issues 

I have used blue Devil and is did not work. Alot of it is the nature of the leak. 

ShawnG said:

Only thing I've had luck with not plugging a rad and temporarily stopping a leak was the powdered "solder seal" stuff.

Ditto. Brand name Alumaseal.

I've used Barr's on several occasions with success on simple leaks. 

I've used Blue Devil on a head gasket. It also worked. 

She should find an alternative mechanic that will at least look at it and diagnose it.  Could be something simple like a hose, overflow tank or radiator.  Those are relatively quick and easy fixes that any mechanic can do.  

"A couple weeks before I can get to it," usually means "I don't want to do this job."

I'd say the stop leak stuff is worth a shot if it's a last ditch effort for something like a small head gasket leak or a heater core leak, i.e. a job that sucks so bad that you're not realistically going to do it. 

Stop leak will stop leaks, but . . . when a mechanic gets to the car will he be able to find the leak that is no longer there?

Also, how big of a flow will stop leak fill? Will it also plug up the radiator?

I used Alumiseal on my '66 Dart; it worked for about a year before the heater core started leaking again. These seem to buy time rather than being a permanent fix - at best.

Blue Devil horse-berkeleyed the heater control valve and the trans cooler thermostat in my E60.  Both were full of smurf jizz when removed, and the rubber seals in HCV were so swollen they partially extruded from their homes.

I've used Barrs on various cars over the years, even on one of the cars that the top tank (plastic radiator) was separating from the core. It was still sealed one I finally got around to replacing the radiator several weeks later.

I accidentally stabbed the new radiator in my van while being a Gorilla and the core had this wet spot in it. I used Barrs on that. It's been over a year no leaks, including towing the race car up steep grades in 105 degree weather.

While it's not the right way to fix something................it does fix it. I keep some in my road trip kit.

L5wolvesf said:

Stop leak will stop leaks, but . . . when a mechanic gets to the car will he be able to find the leak that is no longer there?

Also, how big of a flow will stop leak fill? Will it also plug up the radiator?

If it's a head gasket (as I suspect most are), it should be pretty obvious.

If you follow directions, you will flush out most all of the non-used leak stopper, so there should be no plugging issue.

E.g.  it's not like the stop leak for tires.

Nothing is more permanent than a temporary fix that keeps working.