It won't make any difference. Now PetroChina and Sinopec have reached a nationwide oil resource conversion agreement, which means that the oil of PetroChina and Sinopec should all come from the same refinery or oil depot, so there is no problem.

However, you should distinguish between PetroChina and Sinopec's franchised gas stations. Although it is packaged by PetroChina and Sinopec, it is privately owned. It does not rule out the possibility of purchasing goods from other channels, nor does it rule out the problem of oil quality.