I own a 2000 Dodge durango with a 4.7 L V8. it has 139075 miles on the
odometer. I change the oil religiously (every 3,000 miles or three months) but
it seems to have a cold knock uppon start up, it lasts between 25-45 seconds and
goes away. i send in used oil for analysis to monitor the engine wear and so
far nothing abnormal. I was told that the knocking sound was "a classic mopar
knock" I was also told that it was the hydraulic lash adjusters, and the
secondary timing chain adjusters were a little loose causing the timing chains
to slap until adequate oil pressure was achived. Those were just answers that
some of my friends told me. I want to know what is causing this. do I need a
new engine? I know the oil pressure is good because i hooked up a seperate oil pressure guage in line with the oil
pressure sending unit and found that at idle (600 RPM) was 20 psi and at wide
open throttle (4500-5000 RPM ) was 80 psi. The specs in the service manual
show 3 pisi @ 600 RPM and 80 psi at 5000 rpm. So oil pressure is fine, engine
is clean (no traces of sludge) has the same amount of power it did from when i
drove it off the lot in 2000 with only 6 miles on it! Again is my engine junk?
I certainly hope not, or is this just a minor thing with those sohc 4.7 V8s?

 

I wouldn't be too concerned with it if I were you. You are doing the right thing by sending your oil off for analysis and if anything were to arise you will know long before it would be a huge problem and could address it then.

 

The oil filter probably has no anti siphon valve or is malfunctioning. This causes the oil to drain all the way back into the oil pan. So after it sits for some time when you start the motor the oil pump has to fill up the filter then pump all the way through the motor before getting to the top. This is what is making the sound. The moving valve train and pistons have no lubrication.
Make sure there is a valve in the filter and switch over to Full Synthetic Oil. I really like Mobil One 10W-30. Use ONLY Full Synthetic and not Blended. Blended doesn't to crap.

Fully Synthetic Mobil One flows like water to -58 F and can get to the internal engine parts faster because of how it's made. With this cold weather and also "139075 miles" the added ware are making haste on the motor. The sound you are hearing is the motor waiting to be lubricated. It's dry and dry parts are making the sound. The problem with this is that it wares out the motor real fast.

Let me recommend Mobil One Fully Synthetic 10-30 and a good filter of your choice. Make sure the filter has a anti drain valve in it.