Why is the oil change interval so different GEN 3vs4

After another overfilled oil change form the dealer I drained it the next day. Replaced with Valoline 0 20 and a new filter. I did the next oil change myself too, and after 4000 miles the valvoline still looked way cleaner than what I drained out after the dealer dis service
The Dealers Free oil change for the life of the car was not a cheap add on to the cars MSRP.

Recycling when done properly is good for a lot of reasons. I do a lot of recycling/reusing myself. When done to save money as it's primary objective, not so much.

 

The other thing I've been guilty of - is recycling car engine oil into my lawn mowers and other 4 stroke small engines, been doing it for 40+ years. They always die of something else, never had one die because I didn't use Briggs&S spec oil.

 

My employer 'recycled' Motor Oil in ANFO, with the approval of the US EPA.
ANFO - Wikipedia
The minor amount of metal wear in the oil is actually a plus.

Goldstrike mine - Wikipedia

 

I have s collection of used oil filters that look brand new, but they're a bit heavier than new. I'm still wondering how to best recycle them.
I only have one engine that uses a different thread pitch, thank the engineers for a semi standardized screw on filter. Marketing of oil filters - not so much.

I've only changed one Prius oil filter cartridge on the PiP, and I hope our Prime still uses that system, even if some people have had nightmares trying to get the filter housing unscrewed.

Hammering an big old screwdriver through the oil filter is the tried and true method for getting stubborn filters off the engine.