This would be the biggest discovery of all time, if we actually discovered remains of life on another planet. At the moment and as far as we know, there is no life on Mars and there never has been. It would be fantastic to be proven otherwise, but we cannot rely on hopes of finding oil.

My understanding is that Mars at this time has much less sedimentation than Earth has. It may have had more in the past, but was there ever the volume of organic material that Earth has had in e.g. the Gulf of Mexico or the Tethys Sea?

If we find fossil fuels on Mars, I'm not entirely sure we'll be climbing over each other to burn them. That would be a discovery of immense importance.