I'm afraid it won't do much good to pour a little into the pipe too far away. After pouring, when it is fully reflected, you put a lot of water in it, wash it in, and try to wash all the things inside.

If the restaurant is often blocked, one is that the oil is blocked and the oil can't stick to the pipe wall. The possibility of pipeline damage and collapse is not ruled out. This requires fundamental rewiring or repair.

Caustic soda should belong to something cheaper. Other treasures have pipeline cleaner, which is too expensive. One or two bottles are not enough. You can try it first.