Much of the problem came about when Toyota upped the oil change interval to 5,000 miles. Of course, people used that merely as a guide, and the V-6 didn't appreciate 7,500 to 10,000 mile intervals very much. Sludging ensued.
Of course, people are weird. The Sienna I'll never forget... 39,000 miles. Came to us for an oil change. The oil pressure light was on, which I immediately let my writer know. "Yes. That's why we brought it to you. We've had it since new, and now that the light is telling us to get the oil changed, we would like you to do it."
Yeah.....
No.
I've seen a number of cars that people bought new and just drove until the engine failed. No oil changes, ever. They scream and cry and make threats and eventually GM will give in and warranty it for them, at least partially. The last one I remember the customer brought in some fake receipts for oil changes from an independent shop. Took them a few weeks to come up with the receipts.