Most if not all of the oil companies do not dump it out it is way too valuable. What they do is run it through a filter to get the solids out and then refine it again to be able to resell it to gullible people. I have run the same oil for over a year in my car and have had no problems at all except at the dealerships oil change department.Myopic Bookworm wrote: ↑Sat Jun 10, 2023 9:57 pm (Oil companies have extraordinary dominance in the US. When I lived there, I was pestered to change the oil in my car every few weeks. Here in the UK, I change it once a year, so either American oil is crap quality or the oil companies are pulling a fast one and raking in the resulting profit. God knows where they are dumping all the used engine oil.)

I use a good quality oil and it will last as long as you change the filter twice a year. I had a friend who ran the same oil for almost 3 years just by changing the filter twice a year and adding 1 qt of oil to replace what was lost to the filter change.