I have a Pro Guard 7 drop in filter.
I couldn't see or feel any oil on mine out of the box so I put some on.
AFE oil is a honey amber colour and the filter media is a lighter yellow so you can definately see it when it's applied to a clean filter.
I was cheap with the oil and let the filter sit for 20min so the oil could wick into the filter. Went back and oiled the light spots.
I had to put 3 coats on mine.
You might also want to use a flashlight and check for bits of wire screen trimmings between the pleats. I found 4 pieces on the clean side of mine.