Oil specifications

Car manufacturers test their production in a number of international and national quality institutions of which the most recognized are API (American Petroleum Institute) and ACEA (Association des Constructeurs Europeens d’Automobiles).

API engine oil classification

API classification determines the quality of oil, by experimenting with it in the engine. During these tests, cylinder walls, piston rings, bearings and gas distribution mechanism, formation and cleanliness, burns and deposits, surface damage and oil acidity increasment can be tested. This classification divides engine oils into two groups that are marked with the letters: S – oil for petrol engines and C – oil for diesel engines. The second additional letter (eg., SJ, SL or CG, CH) refers to the qualitative class. The higher it is, the further letter of the alphabet. For example, SL Class oil has better performance than the SJ. Universal oils are marked with general symbols, eg .: SL / CF.API.

For gasoline engines:

Specifications from SA to SH inclusive are not used anymore;

SJ – adopted in 2001; test requirements are the same as for SH, however they are more rigorous for more resistance for vaporization and contain lower quantity of phosphorus;

SL – adopted 2004; test requirements are the same SJ, however they are more rigorous for oil consumption and the formation of burns at high temperature; some of them save fuel;

SM – came into force 2010; for older vehicles, these lubricants are more resistant to acidity increase, formation of burns, better protection from wear and tear, ensure an easy start at low temperatures during their whole period of service; some of them save fuel.

SN – adopted in 2011, these lubricants provides better protection against deposit formation in high temperature on the pistons, better decompose pollutants; some of them save fuel.

It is always possible to use higher-quality oil than specified by the manufacturer.

For diesel engines:

CA to CE inclusive is not valid anymore;

CF-4 – has replaced CE since 1990 lower oil consumption and cleaner cylinders;

CF-2 – since 1994; for two-stroke diesel engines;

СF – has replaced CD since 1994; for engines using fuel with a high sulphur content;

CG-4 – has replaced CE, CE and CF-4 since 1994; for diesel engines to which more rigorous pollution requirements are applied;

CH-4 – has replaced CE, CE and CF-4 since 1994; for diesel engines to which more rigorous pollution requirements are applied;;

CI-4 – presented in 2002; for diesel engines with very rigorous pollution requirements; especially suitable for engines using an additional exhaust gas recirculation (EGR) system;

CI-4 PLUS – presented in 2004; exceeds the requirements for CI-oil;

CJ-4 – came into force in 2006; recommended for use in the newest heavily loaded low-pollution diesel engines using low sulphur content fuel, compatible with both diesel particulate filters (DPF) and EGR.

Higher quality oil than recommended by the manufacturer can be used in all four-stroke engines because higher quality oil ensures better protection of engine elements. It is necessary to take into consideration the manufacturer’s recommendations when selecting an oil for two-stroke diesel engines.

Classification of API lubricants for gearboxes and main drives

Marked with letters GL and a number which indicates the recommended use.

GL-1 – oil for gearboxes operating at low friction speeds. Additives improve the resistance to oxidation, protection against rust, and the congelation temperature is improved with additives.

GL-4 – oil used for gearboxes and main hypoid drives operating at high speeds and low torques.

GL-5 – oil used for gearboxes and main hypoid drives, operating at high speeds with shock loads and low torques or low speeds and high torques.

It is necessary to use GL class oils recommended by manufacturers. For example if we use GL-5 instead of the recommended GL-4 oil, the operation of the synchronizers will be disturbed (slowed down).

API classes are not suitable for automatic gearboxes. It is necessary to take into consideration the recommendations of the automatic transmission manufacturers.

ACEA classification of engine oils

The ACEA quality classification has been used since 1996 and its newest 2008 edition divides engine lubricants into three groups marked with a combination of letters: Ax/Bx – oils for gasoline and diesel light vehicle engines, Cx – oils for gasoline and diesel light vehicle engines with equipped specific gas emission systems, Ex – oil for heavy commercial transport. Every one of these groups is divided into quality levels. E.g. A1/B1, A3/B3, C2/B3 or E4/E7. It is necessary to note that passenger vehicle oils marked with a combination A…/B… or C… are of universal usage and are suitable for both petrol and diesel engines. Besides, a higher ACEA qualification number does not always mean higher oil quality.

For cars with gasoline and diesel engines:

A1/B1 – easy operation, fuel saving oil;

A2/B2 – not used anymore;

A3/B3 – features better resistance to oxidation and film durability;

A3/B4 – features better resistance to oxidation and film durability than A3/B3, for modern diesel engines with direct fuel injection;

A5/B5 – an easy operation fuel saving oil, and features better resistance to oxidation and film durability than A1/B1.

For cars with petrol and diesel low-pollution engines having specific gas emission systems (DPF and TWC) therefore the quantity of sulphur, ash and phosphorus is limited:

1 – an easy operation, fuel saving oil with limited chemical ingredients;

C2 – easy operation, fuel saving oil;

C3 – has better film resistance;

C4 – has better film resistance; chemical ingredients are more rigorously limited.

For commercial vehicles (heavy transport):

E1, E2, E3, E5 are not used anymore..

E4 – stable oil, ensures the longest drain interval (~90.000-150.000 km), it is not suitable for DPF systems;

E6 – stable oil, ensures the longest drain intervals (~90.000-150.000 km) with strictly limited chemical ingredients, compatible with DPF, EGR and other exhaust systems, ultra-low sulfur contents;

E7 – stable oil with the longest drain interval, used for EGR, however it is not suitable for DPF exhaust systems;

E9 – stable, ensures long drain intervals with limited chemical ingredients, compatible with DPF, EGR and other exhaust systems, ultra-low sulfur contents.

Hydraulic oils do not have uniform quality and viscosity classifications. Practically every manufacturer of hydraulic systems and equipment defines special requirements for oil. The most common standards are DIN and ISO.

Classification of DIN 51524 hydraulic oils

The most common are as follows:

DIN 51524 HVLP – lubricants have additives that protect from corrosion, oxidation and wear and tear, plus additives increasing their viscosity index (VI >140, pressure >100 bar). They are intended for universal application, however the biggest advantage is provided when used in external hydraulic systems.

DIN 51524 HLP – lubricants have additives from corrosion, oxidation and wearing (VI >80-100, pressure >100bar). They are intended for universal use and they are recommended for use in internal hydraulic systems.

DIN 51524 HL – lubricants have additives protecting from corrosion and oxidation (VG >80-100, pressure >100bar). They are recommended for use in low pressure internal hydraulic systems.

ISO 6743 – 4 classification of hydraulic oils:

ISO – L – HH Mineral lubricants without corrosion inhibitors

ISO – L – HL Lubricants HH with oxidation-reduction and anticorrosive additives

ISO – L – HM HL lubricants with wear reducing additives

ISO – L – HR HL lubricants with a high viscosity index

ISO – L – HV HM lubricants with a high viscosity index

ISO – L – HG M lubricants with shock resistant features

ISO – L – HS Synthetic liquids

ISO 6743 –4 classification of fireproof hydraulic liquids

ISO – L – HFAE Emulsion, oil-in-water

ISO – L – HFAS Chemical combinations in water

ISO – L – HFB Emulsion, water-in-oil

ISO – L – HFC Water/glyco

ISO – L – HFDR Phosphorus esters – without water

ISO – L – HFDS Chlorinated hydrocarbons – without water

ISO – L – HFDT HFDR / HFDS mixtures

ISO – L – HFDU Anhydrous liquids, more resistant than HFDR, HFDS or HFDT

ISO 6743 –4 Classification of biodegradable hydraulic liquids

ISO – L – HETG Triglycerides (vegetable oils)

ISO – L – HEES Synthetic esters

ISO – L – HEPG Polyglycols

DIN 51506 classification of piston air compressor lubricants