Originally Posted by 328i M-Sport
How are they going to determine a used oil type, assuming it has a reasonable weight? I seriously doubt a dealership would try to send oil to the lab. Not to mention that any decent oil of a reasonable weight can only cause very long term problems.
The things you read on luxury car forums sometimes. I would worry much more about cars with improperly offset wheels, stretched tires, bad alignments due to lowering, screwing up a sophisticated electric system due to poor stereo installations, etc.
Don't be naive.
When facing an expensive warranty claim like a new engine of course BMW is going to measure, test and examine every factor. OIL is one of the first things they'll look at.