Grundöle

Grundöle, in drying and lubricating engineering often referred to as base oils, are the principal component of most lubricants. They determine fundamental properties such as viscosity, lubricity and oxidation resistance, while performance-enhancing additives are formulated to provide additional capabilities like wear protection, corrosion inhibition and detergency. Grundöle do not include additives themselves; they form the continuous phase in which additives are dispersed or dissolved.

Grundöle can be derived from crude oil or produced synthetically. Mineral base oils come from the refining and treatment of crude oil and are typically categorized according to API base oil groups. Group I and II are mineral oils produced by standard refining and hydroprocessing, with varying levels of impurities and brightness. Group III consists of more extensively hydroprocessed minerals and is often marketed as “synthetic” in some regions. Group IV comprises fully synthetic polyalphaolefins (PAOs), while Group V includes all other base oils that do not fit Groups I–IV, such as esters, silicones and glycols.

Production and properties vary by type. Mineral base oils are produced by distillation, solvent refining and hydrogen treatment, whereas synthetic base oils are made by chemical synthesis or specialized processing. Important properties include kinematic viscosity at a reference temperature, viscosity index, pour point, flash point, oxidative stability and sulfur content. These parameters influence performance in engines, gear systems and hydraulic circuits.

Applications range from engine oils and transmission fluids to industrial lubricants and metalworking fluids. Ester-based Grundöle offer high lubricity and biodegradability, PAOs provide good low-temperature performance and oxidation stability, and mineral oils cover a broad compatibility spectrum. Environmental and safety considerations depend on the specific base oil and its additives.