The subjunctive has a few "flavors." It's generally considered formal use so it would be quite acceptable in formal essays.
When something is contrary to fact, you can use the subjuntive. I'm told that this is more common in the US than in the UK, and I have no idea how common it is in other dialects. It looks like the past.
If I were rich, I'd buy that painting. (I am not rich. Contrary to fact.)
If I were you, I'd take the job with IBM. (I am not you.)
If you were rich -- this looks the same as the regular mood.
If he were rich --
Here's text from the OWL at Purdue (Purdue OWL) -One of the best online references I know.
When verbs show something contrary to fact, they are in the subjunctive mood.
When you express a wish or something that is not actually true, use the past tense or past perfect tense; when using the verb 'to be' in the subjunctive, always use were rather than was:
- If he were here... (Implied: ...but he's not.)
- I wish I had something to eat. (Implied: ...but I don't.)
- It would be better if you had brought your books with you. (Implied: ...but you haven't brought them.)
Student or Learner