My 1999 sienna has 234,000 and no serious problems yet!
The 2003 Toyota Sienna gets an estimated 17 MPG (city) and 23 MPG (hwy).
Every 5000 miles, is when I do it on mine.
Change it every 90,000 miles.
I have a 1998 sienna w/160,000 miles. Original owner. I get about 20 around town and 25 or better on highway driving.
The 2005 Toyota Sienna has 24 valves.
The 2013 Toyota Sienna has 24 valves.
The 2010 Toyota Sienna has 24 valves.
The 2004 Toyota Sienna has 24 valves.
The 2003 Toyota Sienna has 24 valves.
The 2009 Toyota Sienna has 24 valves.
The 2014 Toyota Sienna has 24 valves.
The 2012 Toyota Sienna has 16 valves.