You show me a motor head that is going to leave oil (of any kind) in an engine for 25K miles.
There are some here.
I don't understand it, but there are folks here that actually seem interested in seeing how long they can run their oil.
For the cost of doing an oil-change yourself, I can't understand that mentality. It's cheap insurance. If you like driving your car, why wouldn't you enjoy maintaining it well?