I recently bought a CPO 2012 X5d, with about 30k miles. This is my first diesel.

First question: Is there any fuel additive that actually works, e.g. prevent carbon build up etc (or just more snake oil)??

2. I have new Run Flats, but like my last 2 vehicle, I will go conventional tires when these wear out. I have a product in my Harley, call "Run-On", that's a puncture prevention and balancer. Has any one used this in the 4 wheel vehicle ??

Thanks