Oh, that's easy.
Just remove your engine and then take it all apart. Or if you want to cheat a bit you can just pull the oil pan and cut the seal ends longer so they will poke up into the block. Having a bit of crush fit is essential for producing a good seal. I use a small amount of sealer on the ends of the cut seal to prevent small leaks.
All of these seals wear out and then they start to seep which is very normal. A small puddle the size of a quarter after driving isn't too bad and not too much to worry about. A pool the size of your hand is a real problem. If it looks like the Exxon Valdez just crashed on to your shop floor, it's already too late...........
