Definitely a sludgemonster. Sienna is the worse of all because of the additional load on the engine and the tighter therefore hotter engine compartment. I wouldn't buy one used without having a mechanic pull the front valve cover regardless of what maintenance records they may have. A baffle under the oil fill cap keeps you from just peeking in.
Lot's of opinions on the sludging. UOA have shown these engines to really beat up oil. Heads do run hot, oil by design stays pooled in head galleys, PVC has very small opening.
Toyota made modifications to this engine in mid 2001 to "help extend oil life".
Buy a Honda Odessey and sleep at night.
[ December 08, 2003, 10:58 PM: Message edited by: RussellA ]