Mike-
Concerning your thoughts about oil change intervals- I just got done pulling the heads off a 30,000 mile 2003 Avalon at work today because they were full of sludge. The owner only changed the oil 4x in 30K miles. (Thats 7500 mile oil changes!) Now granted they were probably using crappy pennzoil and all, but modern engines (even the 3RZ) are suceptible to oil sludge issues due to tight tolerances and increased operating temperatures. For what its worth, it's MY OPINION (and that of other Tech's at the dealership) that you can't go wrong with the old 3 month/3000 mile oil change interval, regardless of what oil you use. Simply changing the filter will NOT stop the sludge from developing. I know that high-quality synthetic oils don't break down as fast as conventional oil and all, but its so cheap to use a good oil ( I like Valvoline plain-old conventional 10/30, cause it comes outta the pump at work for free...) and a good Toyota filter ( NO FRAM CRAP!) and just change it a little more often.
I've worked on engines belonging to people who use Amsoil/Shaffers/Mobil1/whatever and go for the extended change interval, and they're definitely not as clean inside as those who change it more often.
Just my
Ryan
