I use the 15,000 mile oil in my truck, along with the Mobile 1 filter. On the first run with it, I changed at 5,000, next time was at 7,500, and every time past that it's been every 10,000 miles. It come out looking far better coming out than any other oil that I've changed at 3,000 miles. It works out to be the same price as using cheap stuff every 3,000 miles, but it means two oil changes a year instead of every other month for me.