When I loosened my block drain to change the antifreeze, it opened without having to apply much force, big relief because I thought it might be really stuck like so many other fasteners on this car. Drained OK. Screwed it back in , but it never seemed to get tight. Wants to just keep turning. It's more than finger tight, but certainly not wrench tight. Filled it with new coolant anyway, seems fine, no leaking even when at operating temp and pressure. Are they designed this way? I'm used to drain fittings that close with a definite stop. Threads don't seem stripped; backs in and out OK. And it seems to seal OK.Is this normal?