Mineral gear oils are lubricants produced by refining crude oil. They consist of a base oil obtained from crude oil and an additive package, which are additives improving their properties, for example, resistance to wear, corrosion, or oxidation. Compared to synthetic oils, they naturally have a lower viscosity index. This means that their lubricating ability, i.e., viscosity, changes more significantly depending on the temperature – they are thicker at low temperatures and thinner at high temperatures. For this reason, they offer less protection in extreme temperature conditions. Their thermal stability is also lower, which can lead to faster oil degradation and sludge formation under high load. They are primarily used in older types of vehicles and in less demanding applications, such as standard manual transmissions or differentials, where high demands are not placed on the thermal and pressure resistance of the lubricant. They are a more affordable variant of gear lubricants.
