@dnkboston There are strong signs that what has been thought of as ‘conventional oil’ peaked in 2018. And that the grades of it which support diesel as a direct derivative may have peaked around 2015. And diesel is what does most of the hardest of hard work.
Refinery tech has become incredibly adept at masking this by recombining different oil fractions. But that too is more expensive than not having to do so when the input is of high enough quality…