Lubrication System - General Engine Oil Recommendations

GENERAL INFORMATION

Petrol engines

A – Light multigrade oils with enhanced friction-reducing properties, specification VW-500 00. B – Multigrade oils, specification VW-501 01, or API SF or SG specification. Turbodiesel

B – Multigrade oils, specification VW-505 00

Oil viscosity

Viscosity describes the fluidity of oil. Depending on temperature, oil tends to change its fluidity. As temperature increases, oil becomes more fluid. This reduces the oil's adhesion and resistance to high pressure. When cooled, oil thickens, its fluidity decreases and internal friction increases. For this reason, engine oil should have a viscosity that changes as little as possible with temperature changes.

When starting a cold engine, the oil must be sufficiently fluid so as not to overload the engine excessively and so that after starting, the oil reaches all lubrication points more quickly.

Oil viscosity is equivalent to its internal friction and is designated by SAE (Society of Automotive Engineers) numbers, for example SAE 30, SAE

10. A high SAE number means the oil is thick; a low number characterizes thin oil. However, oil viscosity does not fully characterize the lubricating properties of the oil.

Multigrade Oils

Audi A3 engines use multigrade oils. The advantage of multigrade oils is that they do not need to be selected according to the season. They are based on thin seasonal oil (such as 10W). When heated, this oil is thickened by a so-called "viscosity improver", which ensures appropriate lubricating properties at all temperatures. When using multigrade oil, modern grades with a wide viscosity temperature range should be used, for example 10W–40, 15W–50.

10 is the oil viscosity when cold. The smaller the number, the thinner the oil is when cold.

W (winter) oil is suitable for use in winter

40 is the oil viscosity when hot. The larger the number, the thicker the oil is when hot.

Low-friction oils (high-performance oils) may also be used. These are multigrade oils to which friction modifiers are added as additives along with other components. Light oils use so-called synthetic oils as their base.

Viscosity Grades and Operating Temperature Range of Oil

Since the operating ranges of adjacent SAE grades overlap, it is not necessary to be concerned

CAUTION

for short-term temperature fluctuations. Mixing oils of different viscosity grades is permitted when topping up oil and the ambient temperature no longer corresponds to the viscosity grade of the oil in the engine.

CAUTION

The use of SAE 5W-30 multigrade oil requires avoiding prolonged operation at high engine speeds and high loads. This restriction does not apply to light multigrade oil. CD engine oils, which the manufacturer designates for diesel engines, are not suitable for gasoline engines. Some oils are suitable for both engine types; in this case, both designations are indicated on the container, for example SG/CD. Do not add any supplementary lubricant additives of any kind to the fuel or the oil. Engine oil quality

Only HD oils must be used for modern engines. HD oils are oils with enhanced lubricating properties, improved by various additives. These additives provide better corrosion protection, more favorable conditions against oxidation, the lowest tendency to form sludge, the best viscosity change, and cleaning and dispersing properties. Detergent and dispersant additives not only reduce the formation of deposits in the engine, but also have the ability to dissolve these deposits and all other contaminants in the engine oil and keep them in suspension, so that when the oil is changed these contaminants are removed together with the drained oil.

The quality of HD oils is determined by the API (American Petroleum Institute) system. European manufacturers also follow this system.

Oil grades are designated by two letters. The first letter characterizes the area of application: S – Service, intended for gasoline engines; C – Commercial, intended for diesel engines.

The second letter defines the oil grade in alphabetical order.

The highest grades under the API classification are SJ for gasoline engines and CF for diesel engines.

European manufacturers classify their oils according to the "ACEA" (Association des Constructeurs Européens de l'Automobile) specification, which primarily takes into account European engine manufacturing technology. Oils for gasoline engines of passenger cars have quality classes A1–96 through A3–96 under the ACEA specification, diesel engines have classes B1–96 through B3–96, with A3 and B3 representing the highest quality class.

From model year 2000 (MJ00), as part of the extended service intervals (Long-Life Service), and for the 154 kW engine in AUDI S3 vehicles, new VW/AUDI engine oil specifications apply.

If the required oil is not available, vehicles without Long-Life Service with gasoline engines may temporarily use engine oil meeting ACEA-A2/A3 or API-SF/SG. For turbodiesel engines in this case, oil meeting API-CD specification may be used.