Oil leak sealers

[JALFAjr@domain.elided]

I was in the autoparts store the other day, and saw a bottle of stuff that 
was said to stop oil leaks.  As it was about as viscous as water, I wondered 
how it could do anything. (Being of the old STP school of thought that a 
thicker oil doesn't leak or burn.)

Does anyone have any idea how this stuff is reputed to work?  Does it hit air 
and harden?

Curious in Missouri.

John Justus
1995 164 Q
1971 1750 GTV (being driven almost daily, as the weather has been fantastic 
here in KC)

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