Is it correct that the 2000 Sienna does not have a transmission filter that needs to be changed?

Can I just then drain the current fluid from a simple nut, and refill with new transmission fluid?

Toyota dealer actually urged me to have it flushed.

I have read bad things about flushing, and was surprised to hear this from Toyota dealer.

You won't find any "flush" requirement in your owner's manual or maintenance schedule. That means flush is not a normal maintenance item. I've hear bad things about that.

The dealer don't care about if it's helpful or harmful. They only care about your money. And, if it's harmful to your tranny, they will get $$$ from you very soon for a new tranny. So, of course the dealer want to do it. And although you suspect the tranny goes bad because of the flush, you can never prove it.

Don't do it, unless you hate your tranny.

ProMan's got it right. There's no requirement to flush a tranny, and it's often recommended to NOT do it on high-mileage trannys. A drain/refill is usually sufficient...some will go the extra length to do a double drain/refill since in reality only about 1/3 of the fluid can be drained out. The rest is held in the valve body, pistons, and torque converter.

There is a transmission fluid filter inside the pan. I would say that if the fluid looks and smells okay (not brown, opaque, or burned smell) then you'd be fine not changing it...every 2 or 3 changes is usually good... a few never change it, though I wouldn't advocate it since there is a little magnet on the pan that collects the very fine metal particels that wear off. It needs to be cleaned to keep on removing that stuff from the fluid.

I don't know on your van but older Toyotas have separate transmission and differential fluid reservoirs. I think yours is new enough to have a shared reservoir...but anyone else please chime in with definite info.

Hope this helps!