After reading that interesting thread of the posters' experienes & successes with synthetic oil, the political-economic thing that comes to my mind is could/would it make a substantive change in lessening oil dependency if nearly tout le monde--everybody--uses "synthetic oil?"
I couldn't post this post to that thread as it's been 30 days ... .
And in other words:
How much/what percentage of "synthetic oil" consists of real oil/petroleum?
And how frequently ought the synthetic stuff need to be changed?
I realize this is a nothing new observation/question, but I do not yet personally know the answers.