We suggest that water nanolayers should also be accounted for in future MD simulations of hematite/hydrocarbon interfaces to study adsorption, friction, and velocity slip. While some previous studies have included iron oxide surfaces with hydroxylation 55 or water nanofilms, the vast majority have used anhydrous surfaces. One caveat to this recommendation is for high-temperature applications of hematite/hydrocarbon interfaces, since previous experiments suggest that surface hydrophobicity is restored above 60 • C. One application where anhydrous surfaces may be more appropriate is engine lubricants, as their operational temperature often exceeds 100 • C, 58 so any surface-bound water and hydroxylation is likely to be removed. We also expect our nanoscale insights to be relevant to the interfaces between hydrocarbons and other oxide surfaces (e.g. silica, 23 alumina, 23 quartz, sapphire, 24 and mica ) where water nanofilms are also known to form.