On my Ford thermostat housing gaskets, I just use plain ordinary good contact cement to hold the gasket on which in turn holds the thermostat in place, in the housing (remember that pot metal housing that you broke at 9:05 on a Friday night? And your girlfriend was waiting for you to pick her up at 10:00 after work at the grocery store. And you didn't make it? ). I have yet to have one leak. Any other gaskets that require a sealer - I'll use the manufacturers recommendations.