I'm preparing to study for the new SAT during my spring break, and I have a couple of old SAT review books (Kaplan 2015-2016 and College Board 2nd edition). I was wondering whether I can use them to study for the new SAT or do I need to go buy a whole new set of books?
The changes to the SAT are profound enough that I wouldn't recommend studying exclusively with review books that adhere to the old format. There are some sections that may be helpful, but there are others that are completely irrelevant to the new test.
Types of review materials in your old books that your should avoid include:
Advice and practice materials for Sentence Completion questions (they're gone)
Anything related to the Essay (it's completely reformatted)
Specific advice on time management (there are only four sections on the test now, the timing is slightly different, and there's more to read)
The Math advice in your old books will still be pretty useful, but keep in mind that there are a few additional concepts being tested (trigonometry), and one of the two new Math sections doesn't allow the use of a calculator. For a full overview of the changes to the test, check out this article.
All this considered, I think you should invest in a review book for the new test to get the most out of your prep. If you don't want to buy a new book, at least make use of the four new SAT practice tests the College Board has put online to make sure you know what to expect.