PETROLEUM HYDROCARBONS

In some cases the same name refers to different fuels in different languages, which can lead to confusion.

For example, in French, petrol is called "essence" and kerosene (lamp oil) is called "pétrole (lampant)".

The table below presents the names of the different hydrocarbons in English, French and Spanish, along with their uses.

OILS

Oils are defined by two characteristics: the viscosity index and the quality index.

Classification of engine oil viscosity

This classification follows the SAE norm, defined by the Society of Automotive Engineers. The viscosity indicates how treacly a liquid is. The viscosity of a liquid depends on its temperature: the viscosity reduces at higher temperatures.

• At high temperature: the viscosity should be sufficiently high to assure the protection of the motor and avoid a break in the oil film.
• At low temperature: the viscosity should be sufficiently low to allow the motor to start up easily.

The behaviour of an oil under these two temperatures is normalized by the SAE grade. The cold viscosity grade is determined at -18°C, while the warm grade is determined at 100°C.

Example: SAE 10W40

where 10W = winter grade (W for winter) where 40 = summer grade

Choosing the correct viscosity grade depending on the range of outside temperatures.

Remark Only multigrade engine oils should be used, which are usually of better quality than single-grade oils.

Classification of engine lubricant quality

The API norm of the American Petroleum Institute classifies oils depending on their quality and performance.

For engine oils this norm is presented by 2 letters:

The first letter indicates for which type of engine the oil is used:

• S - petrol engines (spark plug ignition)
• C - diesel engines ( compression ignition)

The second letter indicates the level of performance, increasing with its alphabetical range:

• SA to SN: for petrol engines. SN corresponds to the maximum quality. Note: SA to SE oils are not compatible anymore for vehicles produced after 1979.
• CA to CJ: for diesel engines. CJ corresponds to the maximum quality. Note: CA to CC oils are not compatible anymore for vehicles produced after 1990.

Most engine oils available on the market can be used both for petrol and diesel engines. Therefore you can find on the jar both norms: API SH/CF.

Summerizing the following example: you may use an engine oil with specifications SAE 10W40 API SH/CF for a Land Cruiser, taking into account the climatologic environment and the temperature range in country of operation.

Avoid mixing different brands of engine oil.

Classification of transmission oil viscosity

The principle is the same is with engine oil, however the scale is not the same for an engine oil or a transmission oil.

For example: SAE 80W90.

Classification of transmission oil quality

For transmission oil the API norm is as follows:

API GL-1, GL-2, GL-3, GL-4 and GL-5. GL stands for Gear Lubicant. Note: GL-1 to GL-3 are obsolete.

The oil GL-5 is generally used for the differential, while GL-4 could be used for gear boxes and transfer boxes. Refer to the user manual of the manufacturer in case the MSF standard maintenance logbook specific to your vehicle type is missing.

A differential with a limited slip requires a dedicated lubricant.