The adsorption and self-assembly of surfactants at solid-liquid interfaces plays a key role in a wide range of technological processes, from nanoparticle stabilisation to ore flotation. In tribology, the adsorption of polar lubricant additives from nonpolar base oils onto solid surfaces is critical to their effective operation. For example, organic friction modifiers (OFMs), such as stearic acid (SA), adsorb and form thin (∼2 nm) self-assembled monolayers (SAMs) on steel surfaces, which significantly reduce friction and wear. Similarly, inorganic friction modifiers, such as molybdenum dialkyldithiocarbamate (MoDTC), adsorb and decompose to form thin (∼1 nm), low-friction lamellar molybdenum disulphide films on steel. Moreover, antiwear additives, such as zinc dialkyldithiophosphate (ZDDP), adsorb, form SAMs, and decompose on steel surfaces to form thick (∼100 nm) protective tribofilms, composed mostly of metal phosphates. Modern lubricant formulations contain at least ten different types of additive dissolved in a blend of base oils. Combinations of different additives often behave antagonistically, that is the additive blend gives poorer performance than any of the individual additives alone at equal concentration. Prominent examples of antagonistic lubricant additive combinations include overbased calcium sulphonate detergents with ZDDP, succinimide dispersants with ZDDP, and MoDTC with ester OFMs. Many of these antagonistic interactions are due to competitive adsorption processes, whereby the most surface-active component occupies the majority of surface sites and inhibits the action of the other additives. Therefore, it is important to understand the relative adsorption strength of the various lubricant additives from base oils on steel surfaces.