According to the following article:
http://www.boston.com/cars/news/articles/2007/04/01/carmakers_increase_oil_change_intervals/
In 2004, Toyota (Lexus) reduced the oil change interval from 7500
miles down to 5000 because of engine sludge concerns. Toyota first
blamed the owners forgetting to change oil (don't Lexus have reminder
lights?) and then it's more people driving under severe conditions.
And then the oil change interval got cut by Toyota while others
increased it. What gives?
(I believe Audi, BMW and Mercedes use high specification synthetic
oils (no Group III hydrocracked oils), and they go 10,000-20,000 miles
with no problems.)
