There are alot of posts on this on this issue. Here's one I started a while back.
Toyota Sludge Prevention
The official line from Toyota is that there was never a sludge problem with these engines if proper maintenance was followed, however in mid 2002 they modified the PCV system and baffles in the valvecovers to help extend oil life in the event of poor maintenance. The Toyota engine replacement policy applies to the 3.0 L v6 made from 97 -02.
There are several theories around the Toyota sludge problem including
1) cam gear design sheers oil
2) head temps were increased to meet new emission standards
3) head was designed to keep oil up around the valve train to pre-lube on start up but it cooks oil when engine turned off and oil sits on hot heads.
Changes in 2003 to the 3.0 L V6 don't appear to address these issues. Better safe than sorry. I would search this site for recommendations.
Personally I plan to change from my current use of Amsoil 0w30 to Red line 5w30 because Terry has had good luck with it in these engines. Then after a UOA or two with Terry's analysis I most likely will start the maintenance dose of Auto-rx.
The new 2004 Solara has the 3.3 L v6. I believe this is a completely redesigned engine and hopefully does not have any sludge problem.
[ August 11, 2003, 12:09 AM: Message edited by: RussellA ]