The only Toyota engines "prone" to "gelling," as Toyota referred to their sludge problem when they extended the warranty, was with engines build with a "new" head designed to improve emissions. The head was basically changed back to the previous head design for engines built starting in October of
3003. Engines built after that date have not shown to be problematic. In addition Toyota now recommends synthetic oilIIRC Audi has 10,000 mile intervals, BMW 15,000 miles, Porsche and Mercedes 20,000 miles, but these use synthetic oil meeting strict specifications (VW 502.00/505.01, BMW LL01/04, MB 229.5/229.51).
Therefore I think the sludge tendency is still there with all new Toyota/Lexus engines, that's why you have to change oil at 5000 miles.
formatting link
For Lexus/Toyota:
>
> 2.2 L 4-cylinder ( 5S-FE )
>
> Models and years:
>
> 1997-2001 Camry
> 1997-2001 Solara
> 1997-1999 Celica
>
> New Warranty Coverage: 8 years / unlimited mileage.
>
> Oil drain intervals for warranty coverage:
>
> 5,000 miles/four months (severe)
> 7,500 miles (normal)
>
> ^^^^^^^^^^^^^^^^^^^
>
> There's a second engine for Lexus/Toyota:
>
> 3.0 L V6 ( 1MZ ) [Actually "IMZ" appears, but the "I"
> must be a misprint. It's gotta be 1MZ.]
>
> Models and years:
>
> 1997-2002 Camry
> 1999-2002 Solara
> 1998-2002 Sienna
> 1997-2002 Avalon
> 2001-2002 Highlander
>
> Same warranty coverage and oil drain intervals as the first
> Toyota engine above.
>
> Sidenote: The 3.0 Liter V6 1MZ engine was used in some 2006
> Camrys, so I don't know why the '06 model year doesn't appear
> in the list above. The Amsoil document is copyrighted 2008,
> so it shouldn't be a matter of old information. Was the sludge
> problem somehow fixed in the 1MZ after 2002 ?