Can 从来 mean since forever?
从来 is usually translated to "always, at all times, all along, from the past till the present". But it's usually used in the negative sense, which makes it more like "never".


No, it is '从不' or '从来不' that means 'never'


  it made me wonder if "since always" would be a better translation than "always", since 从来 has the sense "from the past till the present".


'since always/ from the beginning' and 'always' basically express the same meaning

'from the beginning' is the literal translation of '从来' 

'since always/ forever' is the practical translation of '向来/一向'

'always' is the practical translation of '总是'


  So, my question is what do you think about the the following translations:
  
  I always buy oranges. 我总是买橙子。
  
  I buy oranges since forever. 我从来都买橙子。
  
  I always bought oranges (now I don't buy anymore). 我以前总是买橙子。


我(总是)买橙子

我(向来/一向) 都买橙子

我以前总是买橙子


  I have been searching for affirmative 从来 examples (which are very hard to find) 


Here are some affirmative 从来 examples:

(从来)只有我欺負人

(从来)太陽就由東方升起 = 太陽(向来)就由東方升起

採訪部和編輯部(从来)都是各自獨立 (从来 can replace 向来/一向, but using 向来/一向 is more common in this context)

Edit:


  What would be the translation for 我从来都买橙子 then? How is it different from 我总是买橙子? 


"我(从来)都买橙子" = " (from the beginning), I have been buying oranges"  meaning you have been buying oranges for a long long time, but again, "向来" or "一向" are better word choices.

"我(总是)买橙子" = "I (always) buy orange" (not apple, not pear, just orange)