Understanding difference between conditional and subjunctive
I am having a difficult time understanding the difference between "conditional" and the "subjunctive." For example, "I would have bought a new car if I would have won of the lottery." Is any of that sentence subjunctive or is it all conditional?
Another actual example arose today in a slightly different context in which the conditional was not involved. My wife was looking for a new car. I sent her the following message: "Espero que las cosas van bien en tu búsqueda para un coche nuevo."
Then it occured to me that because "hope" was involved, perhaps I should have said: "Espero que cosas vayan bien en tu búsqueda para un coche nuevo."
My instinct tells the the first is correct but I am far from certain.
I hope this isn't too complicated to answer in this forum. In addition, if there is anything else wrong with my grammar or syntax, I'd love to hear it but not at the expense of an answer to my primary question.
Bob
10 Answers
Valerie, this is in a perfect world, like using were in the subjunctive in English, which many natives don't do.. 
Past time situations. Past perfect subjunctive in the “if” clause, conditional perfect in the main clause:
Si la hubiera visto, habría dicho algo. (If I had seen her [I didn't see her] I would have said something.)
Si hubieras venido, te habrías divertido mucho. (If you had come [you didn't come] you would have had a great time.)
This is perfect, however, in Spanish both sentences in the pattern can be correctly placed in the subjuctive:
si la hubiera visto hubiera dicho algo. Si hubieras venido, te hubieras divertido mucho.
This was said on WR by Lazarus:
Si lo hubiera sabido, lo habría hecho- If I had known, I would have done it.
¿Se puede usar hubiera dos veces en la misma oración?
Sí, pero es mejor usar el condicional para el segundo verbo.
He said this here somewhere too, but I cannot find it now.
So, the perfect choice: conditional. But both sentences in subjuntive are very normal and correct in Spanish.
Thank you all. I love the feedback. I made me realize that the question about the would properly be worded:
"I would have bought a new car had I won the lottery."
In English the first clause is conditional/indicative and the second clause is subjunctive but I don't think I would have seen this were it no for the input from all of you. So the same would, I assume, be true in Spanish:
Bob
But I thought that the two clauses had to be separated by a relative pronoun. That does not seem to be true in English. "If I were the president, I would propose a better healthcare plan." "Were" in this case is in the subjunctive mood but there is no relative pronoun.
Note that you have to be careful in using "were" in this way because, thanks to teachers' unions, there are English teachers who will tell you that "were" is incorrect in the above sentence.
Hi bob, welcome to the forum 
Have you looked at some threads about subjunctive?
The declaration rule mentioned by Lazarus is the best to use.
"Espero que cosas vayan bien en tu búsqueda para un coche nuevo."
that's it. Here you are not declaring but hoping for something. Good job, you found that out yourself.
I would have bought a new car if I had won in the lottery.
Written like this it sounds like examples given in textbooks of a construction that requires the conditional in one clause (wherever you find 'would' = my shortcut), and the subjunctive in the other.
This site: http://users.ipfw.edu/jehle/courses/condic.htm is one place to find such explanations. To save everyone the trouble of scrolling almost to the bottom of the page, the following is an excerpt:
An unreal or contrary-to-fact condition is one which will not come about or is viewed as being completely hypothetical. In this case, the “if” clause in normally in a past subjunctive tense, and the main verb is in a conditional tense.
and...
Past time situations. Past perfect subjunctive in the “if” clause, conditional perfect in the main clause:
Si la hubiera visto, habría dicho algo. (If I had seen her [I didn't see her] I would have said something.)
Si hubieras venido, te habrías divertido mucho. (If you had come [you didn't come] you would have had a great time.)
So, I almost thought I had learned this... and now Heidi says that sometimes it can be subjunctive in both clauses. :( Some further explanation Heidi (or anyone)? When should both clauses be subjunctive??
If I am having a difficult time understanding the difference between "conditional" and the "subjunctive." For example, "I would have bought a new car if I would have won of the lottery." Is any of that sentence subjunctive or is it all conditional?
I would have phrased that sentence like this:
I would have bought a new car if I had won in the lottery.
I have been told that this is not entirely wrong , your sentence I mean, but if you had to take an exam here, this would not be considered correct.
Anyway, like I wrote it, the first part is conditional and the second part is subjunctive.
In Spanish:
Me habría/hubiera comprado un coche si hubiera ganado en la lotería.
In Spanish the difference is not so clear as you can use both: subjunctive and conditional in the first part of the sentence.
I"m still not sure I understand but I'll read the other threads.
this has always confused me too. Thanks for the post.
When should both clauses be subjunctive?
One instance that comes to my mind is if the verb in the main clause (non-if) follows a phrase that always requires the subjunctive (a menos que, hasta que, con tal que, etc.)
"I would have bought a new car if I would have won of the lottery." Is any of that sentence subjunctive or is it all conditional?
This should be subjunctive (I believe) because the idea that you would have bought the car is only on the hypothetical condition that you would have also won the lottery.
Turning the sentence around, you are saying that
If I would have won the lottery (hypothetical condition) then I would have bought a new car (this is what would have happened had the hypothetical condition come true so it requires the subjunctive)
To put it in the conditional, (I believe) you would need to say something like:
I would have bought a new car but I didn't win the lottery.
