Ok I had posted a while back about my truck making a knocking noise once it reached operating temp.
I was given the truck (2000 4.6 4x4) knowing it had some issues but it was still free.

I found out my oil is low and black & burnt. Very much in need of a change.
My question is: Now that I know it was from non changing the oil this knck was introduced, what could it be ? and can it (motor) actually be saved ?

It knocks from the oil pan under light loads or lower rpm's, only if at normal operating temp. If I stomp the gas it goes away and still has power either way. If I go to the store and park for a while and start it up, the knock is gone until it gets to normal temp.

Whats the worst case scenerio of my problem now ??
It does still have a miss also (which may have been a result of the knocking), with no check engine light reading anything wrong (mis fire etc.)

Should I put a heavier weight oil in to see if it goes away ?

Also when I do my oil change should I run some kind of engine cleaner ?

I know so many questions but I really like this truck and dont want to screw it up any more than it is...

 

Does it knocks for a few seconds at start up? Does it knock when warm in neutral at 2000 rpm while feathering the gas. Does it knock under heavy load at 2000 RPM.-------------------------- Probably a rod or main knock, could be wrist-pin. Either way major expense at a garage. Change the oil and use a motorcraft filter and go from there. Slim chance could be carbon on top of pistons.
DO NOT USE ANY ENGINE CRANKCASE CLEANER by using engine cleaner on an engine in this shape you end up breaking loose lots of carbon and sludge that only ends up in small oil galaries causing parts failure. By using cleaner poured through the air intake you wash the carbon off the piston tops but you also wash carbon from behind rings in the piston grooves causing the rings to no longer fit correctly in the cylinder causing heavy oil usage and reduced compression. My brother ruined an old chevy that ran great by using engine cleaner, afterwards it knocked and smoked like a steam engine.

 

It's a shame that a 2000 year truck has been abused this way.
If heavier oils does tend to quiet the knock down then (i hate to say this), to keep running the truck over more time before making a decision on what to do about it, is to use additives like Lucas in about a 2 qt replacement to the oil total.
There would be nothing more to lose at this point except more difficult starting in very cold winter temps.

 

Does not knock at start up.

Knocking only occurs once warmed to normal temp. (In neutral,feathering the gas, light load, all of the above)
Its weird though because once I let it cool down (even 10mins) the knocking goes away until normal temp is reached again.
Wouldnt a rod bearing or main cap knock exsist in all scenerio's ?

I used a stethiscope once warmed and it seemed to be coming from the rear of the engine, right where the trans connects. At first I thought it was a bad cat but never heard one like that before. Then I thought it was a drive chain in the trans (if it even has one) until I finally decided to check the oil wich led me to beleive its in the oil pan.

 

I feel your pain... I had a very similar problem with my 2000 5.4 that got progressively worse until I had to pull my engine and replace all of the bearings and have the crank turned. For the complete job, gaskets and all, I think I spent about $450 but that was me doing all of the work myself in the evenings after work. I think it took me two weeks but about a week of that it was raining and I just couldn't bear to chance pulling that motor out of the shed and into the elements. Anyway, good luck.