We didn't set out to extend our manufacturer's oil-change interval by 500 percent, it just kind of happened. As an added bonus, we figured out a couple ways to extend the life of the engine at the same time we aren't changing our oil.
Believe it or not, there are tons of things that can happen to your oiling system that are harmful to your engine, and most of us just don't pay attention.
Change the oil every 3,000-5,000 miles and you'll be fine, right? Well, you'll be better off than Cappa, who didn't change the oil in Red for 80,000 miles or whatever it was. But there are still a lot of concerns that aren't addressed with a simple oil change.
Damage to the engine due to lack of oil filtration can be broken down into two major types of failures: failure of the filter to filter the oil, or failure of the oil to lubricate and carry contaminants back to the filter.
Filter
Not all oil filters are created equal. There is a constant trade-off between restriction and filtration. Filter really, really small particles, and the restriction across the filter goes up-possibly starving your engine of oil. Cut down on the restriction too much, and nice pieces of metal, dirt, and soot get to freely ride around your engine, damaging things as they go.
To get a filter "SAE approved" it needs to meet the SAE standard J1858, where particles of a contaminant are collected before and after the filter every 10 minutes, then counted. Most paper filters only filter 50-60 percent of the gunk under 20 microns.
The next thing going on inside your filter that can significantly damage the engine is called the bypass valve. The bypass valve bypasses the oil filter when it gets clogged enough to reach a preset internal pressure. Actual mileage varies, but what this means is that 100 percent of all particles are circulating through your engine, and the oil filter just became a show piece. It does this for self-preservation; if it didn't bypass at a certain pressure, the pressure inside the filter would become so great that the filter would explode.