Hi GMATmona07.
Generally, it's helpful to practice using older OG questions, for a few reasons. One is that, as bb said, generally, the older questions are not that different from the newer ones. Another is that, to a large degree, you are practicing to develop precision in execution. So, even if the style of a question is a little different from the style of a question that would appear on today's GMAT, the question can still be useful as a means of developing precision.
That said, there is one area in which using older questions, while useful, can also be a little strange at times, and that area is Sentence Correction. Around 2010, GMAC switched from one SC question provider to another and also made some adjustments to what SC questions involve, reducing the use of less well known idiomatic structures in SC questions, making SC questions more logic focused, and improving the quality of SC questions. Also, SC questions had been evolving even before then. So, whereas we could say that math remains math, SC has changed over the years. Older SC questions tend to be lower in quality, be more formulaic, and involve more so-called "idioms" than today's SC questions.
Long story short, you can still learn from most older official SC questions, but some are not great.