[Rick Lee]

BMW's recommended intervals only got to 15K miles when they started offering the maint. warranties. Before they did that, the gospel was that you couldn't change your oil too often. Once they started paying for it, 15k miles became ok. I change it every 5k. And I suspect the previous owner went by BMW's recommendations. Problem is that you can go 15k miles just fine for a few years. Once you start having problems, your warranty will be long expired, so it's no longer their problem.