First of all, before answering the main question, let me say a question: there are huge problems in the fuel oil contract. The futures target is 308 standard high sulfur fuel oil. The new international shipping standard in 2020 requires that the original standard fuel oil with low sulfur fuel oil will not be able to go to sea. This is why crude oil rises near delivery, while fuel oil falls off the cliff. Unfamiliar with contract design is easy to step on the pit.

The next main contract is 05, yes. Many commodities in domestic futures are exchanged among these three contracts: 1.5.9. People are used to changing contracts less and spending a long time to reduce transaction costs.

The main contract depends on the volume, and the volume is the main force.

Generally, the warehouse is moved earlier, bit by bit.