i have a 03 SCrew F150 4.6 and it "rattles" when cold started, it has been doin this for about 60k or more.. it has 225k on it now and runs great, there is no metal in the pan and oil is changed regularly, It sounds like its coming from the lower end. would it be the main bearing? if not whatever it is can it be changed without tearing apart the motor?

 

Not enough info to make any judgement.
What oil and grade have you been using and what oil filter?
Bearing noise is very specific as opposed to a rattle.
Some people call bearing noise rattle but it's all in what the observer means.
Does it go away after starting and in how long a time etc.
Some oil filters will cause bearing noise at cold start due to the time it takes for the oil pump to pickup oil and begin to pressureize the system. This is why the oil and filter used, is important.
Have you had the oil pressure checked to evaluate the oil pump and bearing condition?
I'm sure you understand that repairs internal need the motor to come apart at some point in some form.
Expect anything at 225k miles.
You already got long service from the motor.

 

Motorcraft filter, castrol 5w20 with one qt Lucas and it goes away in a few seconds, it runs great though I'm just lookin for something to mess around with on my free time

 

Sounds like a delay in oil pressure buildup.
The cam chain tensioners depend on oil pressure to adjust and take up tension.
If their guides are worn, this takes more time to take up the slack.
If the main/rod bearings don't get oil fast enough at start you could hear them make a deeper sounding noise until they get oil pressure applied.
Could even be the oil pump failing to build presure fast enough.
At the mileage it has it could be a little of each.
Good luck.