柔軟剤を洗濯機の投入口に入れる時は水で薄めたほうがいいですか?

Should I dilute the fabric softener with water when putting it in the washing machine's inlet?

Normally, there is no need to dilute it with water.
Some washing machines may instruct you to dilute the solution in order to prevent liquid residue.
If there is any liquid left in the inlet after use, we recommend diluting it before adding it.