Due to growing environmental challenges, many studies are focusing on vegetable-based lubricants. Industrial lubricants pose a significant risk to the environment and human health. The tribological performances of calophyllum calaba (galba) and avocado when used as a base oil and as a liquid additive were compared to those of moringa oil. The different lubricant formulations were investigated under an ambient atmosphere, using a reciprocating ball-on-plane tribometer in a boundary lubrication regime. Graphite particles were used as solid lubricant additives due to their excellent friction performances in these formulations. Dodecane was the mineral oil used as a reference and base oil in some lubricant formulations. It was found that the percentage used and the fatty acid molecule composition of vegetable oils have an important influence on the tribological performances of the different formulations. The presence of oleic acid molecules shows a positive effect but is not sufficient to explain the friction reduction obtained with moringa oil. The triglyceride shape of an oleic acid molecule is the key to an important friction reduction, despite the small amount (2 wt% as liquid additive) in lubricant formulations.