I have a 2006 cooper R50 with 49K miles, I have always used either Mobile or Shell gas. I started to use Valero about 3 weeks ago, the Service Engine Light came on today @ half tank. I stopped at Shell and filled up, the light went off and it is staying off. This is the second time I started using a different brand of gas(Exxon) and the light came on, back to shell or Mobile the light stays off. This is just a FYI I hope this works for you!