5. Conclusion

There are thousands of additives that can be manufactured, and several hundred products available in large industrial quantities. These additives may interact with each other in beneficial or harmful ways. Their performance also depends on the nature of the base oils with which they are associated, and the tribological conditions prevailing in the mechanisms for which they are intended. To achieve a given result (i.e. to meet a given cost, schedule of conditions or specification), the formulator can choose from a wide range of possible combinations. This means that the possibilities for formulating highly complex products, which may contain up to twenty different additives, are theoretically virtually infinite. But, in fact, for each formulation laboratory, the choices are fortunately more limited, since they are based on its own jealously guarded experience of an accessible range of additives...