What's causing my 2000 toyota camry to knock upon startup fir a few seconds?

Is it a low end knock or it is a lifter tick .if lifter tick try lower weight oil 5w20.

Not a lifter..more of a low end knock..goes away in a few seconds

How old is oil?

I'm sure it should be changed.thought about changing oil and filter..

That might help.

I'll give it a try thanks..

How many miles on this vehicle. High mileage? May be piston slap.

It does have alot of miles..but...it only does it when ya start it and for just a couple seconds..seems like if it was a piston slapping it would do it all the time...idk..

When piston slap begins to develop, it knocks when cold, then goes away when the piston warms up and expands. You might be able to isolate this noise by disconnecting power to one cylinder at a time and see if the knock disappears. This of course will take several cold start ups. As noted above try changing the oil and filter and see what happens. I would not worry much at this time. High mileage engines will eventually develop noises.

I can't imagine it warming up in like 2 seconds..I am gonna try seafoam followed by an oil and filter change and see how that does...thanks for all the answers guys!!!I'll post after I try that if I'm able to...