Providing evidence for possible oil-type occurrences on Mars means providing an indication for the past life on Mars. We do this via analysis of the combed (aligned) gravity strike angles, one of the gravity (gravitational) aspects (descriptors) derived from one of the recent gravitational field models of Mars, currently having the highest accessible precision and resolution. After intensive testing for features on the Earth and the Moon, the gravity aspects are applied for Mars. We detect candidates for the groundwater/hydrocarbon/mud/petroleum-bearing sites in the largest areas with as many as possible combed gravity strike angles, uniformly ordered into ‘plates’. They appear mainly but not only in the hypothetical northern Martian palaeo-ocean (the northern lowlands). It turns out that the combed strike angles are sensitive not only to uniformly ordered sediments of the basins, but also to supposed lahars.