urethane gasket sealers

[68pont455]

has anyone used urethane gasket maker or sealers instead of conventional silicone? i know my chrysler concorde engine used it in place of alot of gaskets. the oil pan for one used urethane sealer instead of a tradition gasket. it was leaking so i replaced it with after market gasket and sealer and still have minor issues with it but that is another story. has anyone sealed an entire engine with it without having problems later. this stuff was a bear to get off. i had to use prybars and a knife to get the pan off. just interested in opinions.
thanks
zac