Lubricants for internal combustion engines - Manufacturer's specifications

Manufacturers of passenger cars and commercial vehicles, as well as those of power generating units, draw up regularly updated specifications for oils intended either for initial filling, or for in-service filling of engine crankcases. These specifications are used both for the homologation of oils offered by the lubricants industry ("original equipment" oils and service oils), and for the recommendations made to engine users in maintenance booklets or manuals ("service oils").

These specifications are intended to guarantee vehicle and equipment users oil qualities that meet the various lubrication requirements of engines, under all conditions of use and throughout the oil change interval: protection against wear and fouling by deposits formed at high (oxidation varnish, hard carbon deposits) or low temperatures (sludge), ease of starting and good cold pumpability, reduced friction losses, protection against rust and acid corrosion, non-foaming and rapid de-aeration, absence of attack on organic materials present in engines (seal elastomers, plastomers, paints, etc.).).

In their standards, manufacturers require, firstly, that oils meet the specifications of international bodies such as ACEA (Association des Constructeurs Européens d'Automobiles) in Europe or API (American Petroleum Institute) in the USA and, secondly, that they meet particular requirements specific to each type of equipment. These additional requirements, mainly imposed by European manufacturers – American manufacturers are almost always satisfied with API specifications for all engines and ILSAC specifications for gasoline engines – translate into the satisfaction of specific physico-chemical and engine tests, the list of which is sometimes quite impressive (as in the case of Volkswagen, for example).

In addition to OEM standards, this article also covers some US and French military specifications, as well as oil specifications for two-stroke spark-ignition engines.