What does oil have to do with a leaking water pump, which is not lubed by the oil and is driven by an external belt? And the piston slap too, there are no squirters on these engines, that has nothing to do with oil. Now power loss and oil useage, that would indicate a problem but considering the vast amount of these engines, it seems more likely to me that it's a defect in your unit, than a failure of all 5-20 motor oil. I mean, take a look out the window the next time you're driving. Consider the numbers.
So twice we have an engine that's completely dead, but manages to propel the vehicle fine.... and you were able to trade it in so obviously it wasn't that bad.
I don't blame you for not liking Toyota, but to blame the oil is ridiculous.