[ConservativeMind]

Our refineries are not tuned for all oils we extract. We have been refining crude from other countries and need to closely meet that same type of oil to crack it, unless we take refineries off line for months to adjust back to local crude quality. That amount of offline time would really drive up prices,and then OPEC would again be crushed and their cheap oil again could be used, but require another major change back.

[NCjim]

Thank you for your explanation!