Before we go into a long discussion on linguistics, grammar and local spelling let me quickly skip to the main reason for this site’s name: it is a direct quote from Henry Ford´s 1922 autobiography “My Life and Work”. In the book Henry Ford quotes himself as saying “A customer can have a car painted any colour that he wants so long as as it is black”. I own a copy of the 1922 first edition of this wonderful book and it is a constant source of inspiration. So many of his then revolutionary views are still current or even visionary today nearly a century later. But back to the quote…
It seems that today “so long as” and “as long as” are used interchangingly and many even prefer “as long as”; perhaps they find it easier. There are however some subtle differences which I will try to explain as I understand them.
The term “as long as” works as a comparison: “Nobody has legs as long as Ana Hickmann has”. (which by the way are 48inches/122cm). This is a simple comparison. Are their legs as long as Ana’s or not. It doesn’t mean that other girls cannot have legs while she has.
“So long as…” serves as a condition: “Ana hickmann will walk so long as you pay her”. She will only walk if you pay her, but that doesn’t mean that you will have to run next to her constantly handing over cash since it is not a comparison of time like “as long as” would have made it.
Color or colour? Despite Henry Ford being american he uses the English form of colour as opposed to the american color. This is likely because American English had not yet been formalised (or formalized if you are American) when Henry published the book in 1922.