1996 Mercury Villager, V6 3.0L 128K miles, very well maintained, oil changed all the time.
Been dealing with an oil leak at the front main that a local shop twice now has replaced the seal and still leaking. When I left the shop after the motor warmed up I noticed a knock, the sound like it ran without oil. I was assured that they did not do this and that the knock is a rod knock pure coincidental. I was later given a 2nd opinion that it's a lifter based on these facts.
When the motor is cold there is no noise its as smooth as silk and burns no oil whatsoever. After she warms up you start to hear a tapping and when she gets to operating temp it's a pronounced tapping but I would say its kind of hard in sound. When you rev the motor past 1500 RPM the noise totally goes away and only comes back as the motor decelerates back under 1500 RPM. I am told by 3 mechanics that rod noises never go away even cold will make noise and will only get louder as you rev the motor and that lifter noises go away as oil pressure builds as when the engine RPM increases.
When I put a stethoscope to the front valve cover I don't hear as much of a noise as I do when I put it to the back valve cover, the noise seems much more pronounced from the rear valve cover.
Anyone care to dispute these statements or have an opinion on if it sound more like a rod or lifter.
Also been pricing lifters, Autozone wants $13 each, NAPA has 2 prices $22 and $35 one says lifter and one says hydraulic lifter at NAPA, are they both not hydraulic lifters and why such a huge difference in price not only between stores but between NAPA itself? Any ideas, is one part that much different then the next, Oh yea NAPA and Autozone's part number are the same, the $13 and $22 part that is...

Thanks Bill