I personally, would remove " Lamp oil is a very polar substance " And replace it with what the article you wrote, was about. For example, lets say you wrote about why people love ice cream, you could have the ending sentence say. " And that's why I wrote about why people love ice cream" Or something along those lines. I'd write a few more facts about it first, don't just have one sentence saying a fact without any supporting detail, hope this helps! :)