Viscosity of engine oil (Opel Kadett D)

Viscosity is the fluidity of the oil. Depending on the temperature, the viscosity of the oil decreases. As the temperature increases, it liquefies. This has a negative effect on adhesion to the surface and the strength of the lubricating film. As the temperature decreases, it becomes thick, while the viscosity and internal friction resistance increase. These properties require the use of oil whose viscosity changes as little as possible with temperature changes. When the engine is cold, the oil should be liquid enough so as not to overload and hinder the starter and to get to all lubrication points as quickly as possible. Viscosity and internal friction of oil are the same thing and are designated by the SAE system (Society of Automotive Engineers), such as SAE30, SAE 10, etc. A high SAE number indicates a thick oil. However, viscosity cannot be used to determine the lubricating properties of the oil.

All-season oil

For OPEL KADETT D, you can use both seasonal and all-season oil. All-season oils have an advantage because they are suitable for both winter and summer. All-season oil is made on the basis of low-viscosity seasonal oil (for example, 15W) Thanks to the so-called thickener, the oil is stabilized in a hot state, so that under any operating conditions it produces the required lubricating properties. If all-season oil is used, then preference should be given to modern oil with high viscosity (for example 10W-40, 15W-50). The letter "W" indicates that the oil can be used in winter.

All-season oil with enhanced anti-friction properties (light water)

This is an all-season oil with additives to reduce the coefficient of friction, which means that fuel economy increases by 2%. These oils have a low viscosity (for example, 10W-30). They require an unconventional basis (synthetic oil). Sliding oils must meet API specifications.

Purpose/Viscosity classes

Since the areas of application of the oils overlap, short-term temperature drops are permissible. It is also permissible to mix oils of different viscosities when topping up, or when the air temperature does not correspond to the viscosity of the poured oil. At prolonged temperatures below -20°C (arctic region) it is recommended to use SAE 5W20 oil.

There is no need to add additives of any kind to either fuel or oil.

Engine Oil Specification

Oil quality is classified using the API system (API = Amehcon Petroleum Instilut). European manufacturers also follow this system. The name of the oil necessarily contains two letters. The first letter determines the area of use S = Service, suitable for gasoline engines, C = Commercial. suitable for diesel engines



(Text copied from an internet website: OpelBook)

The second letter defines the quality in alphabetical order.

The best quality oils are those of API specification SG for gasoline engines, CD for diesel engines.

Attention: CD oils, which manufacturers recommend exclusively as oils for diesel engines There are oils that are suitable for both gasoline engines, and diesel engines. In this case, both designations are indicated on the container (for example SF/CD).

For OPEL KADETT, SG API specification oils are recommended, SF oils are acceptable.