Although changing font in OS X El Capitan It has been a breath of fresh air, it does not always rain to everyone's taste and for this very reason many users unfriendly to change and accustomed to the Lucida Grande type of font, they want this to continue as they are not convinced by San Francisco.
In a certain part they are right because the legibility of Lucida Grande in my opinion is greater in specific circumstances where the text is smaller or if we have a document with a lot of text to read. However, I like San Francisco more in absolute terms, that is, in general it matches better with the new style of the system and meets perfectly in most cases, ultimately a matter of taste.
The change is possible thanks to a small project published on GitHub by a developer and that add this type of font to the existing ones in OS X El Capitan by means of a Script, clarifying that it does not modify any system file, but adds the necessary ones to set Lucida Grande as the default font.
Even so, whenever we are going to modify certain parts of the system, it is highly recommended that we previously carry out a backup of the system either with Time Machine or with any other third-party program. The application you can download from this link, which will give us the possibility to install the font on the c systemHow to uninstall it and clear the cache to return to the original.
In any case, it must be clarified that it still suffers from some bugs and on certain occasions the text is practically mounted, that is, the letters stay too close together affecting the reading, such as when we open too many tabs in Safari. Hopefully this is quickly fixed and that those who longed for the old typeface have an alternative using this method.