Why would duke oil filter be empty?

I have an ‘84 Fiero with a duke here that I bought 4 ½ years ago. The engine ran when I bought it, but it had clutch problems, so I had it towed here and it’s sat ever since waiting for me to get at it.

Well, I finally have a chance now to deal with it. I thought I’d better "prep" it before trying to start the engine after not having run it at all during these last 4 ½ years. I drained the oil, which looked brand new, and I also wanted to change the oil filter.

I was rather shocked to find only about a tablespoon of oil in the old oil filter  (which also looked brand new on the inside).

I’m kind of stumped as to how the filter could have so little oil in it. As you know, with the angle the oil filter sits at, the oil can’t drain out of the filter. Is there any chance the oil could of somehow siphoned out of the filter over the last four years?

Or is there a chance that when I heard the engine run (for a few minutes) at the previous owner's place, that oil wasn't actually making it to the oil filter? Is that even possible?

I’m rather reluctant now to try starting the engine until I get some feedback on this.

Anyone come across this before?