I have that same engine in a 2003 Sienna.
You are in the "gelling" range of years for this motor.
It is VERY important that you verify that the PCV system is working......that the PCV line is actually pulling air from the motor.
If this becomes clogged.....PCV valve or buildup in the valve cover/motor preventing airflow, then your oil will "gell" in short order.
I am running Redline oil in my Sienna, and plan 5K OCI, which is overkill.
The Royal Purple should serve you very well.
I have a '96 Ford Windstar, and found out that the oil filter for it is IDENTICAL in specifications to the filter for our 1MZFE motor except that it is longer.
If you are into longer filters......here is a comparison of filter numbers for several brands.
2003 Sienna / 1996 3.8L Windstar
Bosch 72161 / 72143
Bosch Premium 3330 / 3422
WIX 51348 / 51516
ACDelco PF53 / PFL400A
Fram X2 XG3614 / XG3600
Mobil 1 M1-102 / M1-209
K&N HP-1002 / HP-2009
Purolator PL10241 or L10241 / PL20195 or L20195
These are certainly not the only quality filters that would work, just some that I crossed.
I have the Wix 51516 on mine right now.
In short, it is a great motor, and should serve you well as long as you keep an eye out to prevent the "gelling" issue.