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

Try 5W-30 full-synthetic engine oil (e.g. Mobil 1). From your description, it sounds more like a lifter problem. Synthetics may clear this up fast--I've seen it happen.

I had been using mobil 1 from around 34K until 125K but because of the oil leak I had to go back to conventional oil. This leak started last summer, the front main started which was replaced and the cam seal started so that was replaced along with the water pump and timing belt, then the rear main started leaking. Which I understood because as the motor started sealing up building pressure the oil looked for a way out and suspect seals were the way and the rear main was the only one not replaced, so even after all the seals were replaced it still dripped oil ever so little, figured if I lost 1/4qt every 3000 I could live with that, but I switched back to conventional only until this leak is repaired, but if I had mobil 1 in there now I am afraid it would not stop coming out as I have to fix this knock if it's a lifter first then the leak, if it's a rod then I probably will junk the van in the end as I don't have the capacity to rebuild the motor in my garage and I wouldn't know where to bring it to have that kind of work done, surly not the people who can't stop a leak...
But yes I am an advocate of synthetic big time...
Thanks Bill

It a shame having this type of problem on such a low mileage vehicle. My brother has a Mercury Villager to haul his 3 kids around. I think he has over 200,000 miles and no real issues. He doesn't take great care of it either.

Have you replaced the PCV valve? That could be the cause of your continued leaky seals; if the motor is building up too much pressure it may be pushing the seals out. Saw it happen to the rear main 3 separate times on a Ranger.

I agree. I can't prove it but I have a strong feeling that they might have tried running the car and realized they didn't put oil in it before they didn't do too much damage and tried saying oh its just a coincidence and I can't prove it. When he said oh it might leak oil for a week residual oil, I was like if you did a leak check how could it leak oil? He said what do you mean leak check? I said well if you cleaned off the area really well before you worked on it as best you could, did the repair work, took it out for a test ride to get the motor up to operating temp then bring it back in and see if there is oil leaking from around the cover plate. I am not talking a little oil dripping from the frame where you can't get to it but from the cover plate and behind the harmonic balancer you would be able to tell if it was leaking fresh oil not old dark oil. I get the van home and in 30 min I have puddle of fresh clear oil in my driveway, now my diagnostic skills tell me that its NOT residual oil... What kind of mechanics are out there these days. What do you mean leak check?? Ohy vey!!
Sorry I didn't rate your answer, I am kind of new to this forum and I am learning, it would let me rate mine, well how fair is that?. lol
Thanks Bill

No I have not replaced the PCV, it's a simple fix and will give it a try, thank you, wonder why the shop didn't think of it...