oil filter empty after 5K miles!?!? Why?

[azex2001]

1990, EFI, 5sp. 409K miles. 10w-40. STP oil filter. I changed the oil this weekend and when I removed the oil filter it was empty (no dirty oil) and clean. I always put clean oil in the filters before installing them, so I could see that it had some oil in it, but it was empty and clean. Any ideas what happened? Thanks.

[WmWatt]

Don't know but I'd remove the one you put in to replace it to see if it's working. If so then the empty one was defective?