I came across the 'stuff' and it sounds to good to be true. Here's the link: http://www.cryochem.com/CRYOseal.html
If there is
a leak and you can eliminate the compressor shaft seal as the source of the leak, the repair can be made without risky guesswork. I don't know what it costs.
Interesting alternative, isn't it? This might have saved you $3K!