I changed the oil in my '87 Hardbody this weekend and have used a Fram Tough Guard filter from Walmart with that rubber flap that keeps the oil from running back through the filter to the pan. They weren't in stock and I wound up buying one from Advance AP without that flap. At start up this morning I heard that old familiar sound again, a short "clackity clacking", valves I suppose. It has 300,000 miles on it and I'm waiting on it to finally quit running before I tear it apart. I didn't put a lot of thought in those flapped filters, kind of a sales pitch thing to me, but I do now! Makes a difference on my truck on cold starts.

Depends on the design of the oil passages and the position of the oil filter. I guess your truck likes the anti-drainback.

On a different, but related note... I've had some filters that DO include that anti-drainback feature where the valve does not work. You can tell when you take the filter off the car that the inner portion has already drained out past the valve. It's not supposed to, but I've found that they sometimes do anyway. Maybe one in twenty?

Yes they do make a huge mess when I spin the filter off. The one I took off yesterday, without the valve, didn't. Oil level stayed close enough too. I'm hoping for a quite start up this morning.

Yeah, that mess is an indication of how well the anti-drainback feature is working.

Here's a couple of my dissected filters. Old style AC Delco before they switched to the plastic filter support cage: (Notice the little split where the filter media was never connected properly at the factory.)

Typical Purolator. Been this way for at least ten years: