Cold Start Engine Knock Noise :(

[Ivanhoe]

Well, my V6 makes a brief engine knock type noise that lasts for about 1 to 2 seconds when I first start it up in the morning.....
I hear the same noise when I start up my cab (2007 Crown vic with 46k)
Fords are known for "lazy" oil pumps, but Ive never known Toyotas to have this problem.....Ironically, my dad just sold a 2003 Sienna with the same 1mz-fe engine and it did the same thing for about 5 to 10 seconds.

Does anybody have an idea what this could be?
Does anybody else experience this?
Do you think switching to synthetic might help?
On my last oil change, I put in 10w-30....maybe the thicker oil is the problem?

TIA!