Looking on the internet deeply has found these results:

as long as is the most popular phrase on the web.

so long as 14,190,000 results on the web	as long as 19,900,000,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Mar 8, 2013 ... I just googled the difference between as long as and so long as. The difference has alredy been discussed here. There are, it seems, two�... As long as or so long as also means 'provided that', 'providing that' or 'on condition that': You are allowed to go as long as you let us know when you arrive. during and up to the end of the time that : while <so long as you are here, I'm fine >. 2. : provided that so long as you return by dinnertime>. See so�... During the time that; while: We will stay so long as you need us. 2. Inasmuch as; since: So long as you're driving into town, why not give me a ride? 3. Provided�...	I mean, this works as long as it's to correct others. Guessing not as long as yours. ' Made him a snout as long as a rail. I'll stay here and run com relay as long as my fuel holds out. Not as long as we remain true to each other. Who cares, as long as the plan works. And as long as I'm cleaning out the family chariot... We hope he stays as long as possible.

so long as

14,190,000 results on the web

as long as

19,900,000,000 results on the web

More popular!

Mar 8, 2013 ... I just googled the difference between as long as and so long as. The difference has alredy been discussed here. There are, it seems, two�...
As long as or so long as also means 'provided that', 'providing that' or 'on condition that': You are allowed to go as long as you let us know when you arrive.
during and up to the end of the time that : while <so long as you are here, I'm fine >. 2. : provided that so long as you return by dinnertime>. See so�...
During the time that; while: We will stay so long as you need us. 2. Inasmuch as; since: So long as you're driving into town, why not give me a ride? 3. Provided�...