Did you explain this to the contacts I gave you?
You only said you were looking for base oil prices for a paper.
LubesnGreases (LNG Publishing) has a one or two page article each month on base oil trends.
You have mineral oils, PAO's, AN's, Esters, and bio oils. For bio-oils one would have to contact people like ADM, CRODA, Arizona Esters, etc. But as a technical writer I am sure you how to do Internet searches already.