The last couple of years, Google search has become increasingly unreliable.
When doing a search Google will list a lot of irrelevant pages that don't even
contain the search words. Furthermore, a lot of new pages no longer get
indexed. Google will only index new pages it considers 'cool'.
If you are looking for commercial products on company websites, Google is probably still OK. But when looking for in-depth technical info you are better off with other search engines.
More here: What's the Best Alternative to Google's Search Results?