In a recent post, I voiced my discontent with the way GM had handled the plenum failure problem in general, and mentioned it might be time to look at a Toyota.
Someone (pardon for not remembering whom) posted that Toyota had also had problems with sludging engines, leading to failure in some instances.
Drove the Toyota today. Wonderfully quiet, smooth, and responsive. Was really impressed.
So I asked about the sludging problem while at the dealership. They confirmed it had happened and gave the reason that many people tried to run too long between oil changes. They said that the manual clearly called for oil and filter changes near the 3000 mile interval, but a lot of people tried to push oils to 7500 and more. And it just didnt work.
This post covers several items, and comments are welcome.