Well - I can't see some snake oil causing a safety issue ... that seems a bit dramatic, but I have never heard of a "stop leak" product for hydraulics, not saying that it doesn't exist... but ...
On the other hand - I am driving a living (?) testament to Barrs Leak!
I have a 2004 'Burban with <400K miles on it. It had recently been replaced as Mamma's primary vee hickle already, and it started drinking coolant. The truck has electrical issues as well, and a scar down one side, so we will not be puting any real $ into fixing it from here out. I was thinking about pulling the heads off and hoping that it was a blown gasket, but I was told that the heads on this motor were known to crack. And then I remember a chum had one with a cracked block.
Well, I aint dumpin' that kinda $ into fixing this thing, so I don't know that I want to tear it down - only to not put it back together.... So I decided that I would try some "stop-leak" and just see what happens...
So I went to the parts store and got the most expensive bottle of juice on the shelf. It was a pretty large can of copper coloured Barrs Leaks (IIRC) and was still only $10 or maybe $20 on the outside...
I dumped the bottle in the overflow tank (I don't think that this truck has a port on the rad).
That was maybe 3 years ago? It is my daily driver, but not for any distance normally. To this day, I cannot recall having added ANY coolant to it since I dumped in the snake oil. Not even a little top it up the day after! I gotta say - I'm amazed!
But I wouldn't expect a hydro system that runs at high pressures to accept the same stop-gap repair that a 13# system will accept.
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Think Snow Eh!
Ox