The engine oils for our climate zone

In the Balkan region, there is a moderately continental climate with minimum temperatures around -20°C and maximum temperatures around +40°C. Excluding about ten extreme days in winter and summer, the temperature range is from -15 to +35°C. Mountain areas are an exception, where temperatures can drop to -25°C.

Generally speaking, and considering the above, the ideal SAE viscosity grades (VG) for year-round oil are:

• For older generation cars from the 1990s (and older), 15W-40 and 10W-40, and for mountainous areas 5W-40;
• For mid-generation cars from the first decade of the 21st century, 5W-30 or 5W-40, and for mountainous areas 0W-30/40;
• For the latest generation cars from the second decade of the 21st century, for the entire area of Serbia and the wider Balkans and southeastern Europe, 0W-20 or 0W-30.

The choice of viscosity grade is primarily related to the engine design and the manufacturer’s recommendation, which also takes into account the climate zone. Therefore, you should always consult the car’s manual where the recommended VG values are indicated. There are two types of recommendations:

1. A single viscosity grade as the default value, typically for some European manufacturers - this takes into account the average climatic characteristics of the entire continent, excluding extreme values such as Northern Europe and areas with a Mediterranean climate.
2. The specified viscosity grade that is primarily recommended, along with a table of recommended VGs for different temperature ranges - this is typical for Japanese manufacturers, even those with production.

Modern cars usually have one (primary) viscosity grade that is most often recommended for a temperature range of -30 to +40°C, which practically covers all of Europe. These are mainly low-viscosity, easy-flowing oils. For European manufacturers, these are mostly 5W-30 or 0W-30, and for American and especially Japanese manufacturers, 5W-20 or 0W-20 (recently also 0W-16). According to the trend of reducing internal resistance, the SAE J300 standard, which defines oil viscosity and VG, was expanded in 2015 to include, for now, future 0W-12 and 0W-8 oils.

For newer generation engines, the use of more viscous oils can be counterproductive, as even with 5W-40, bearing lubrication can be significantly worse. Therefore, one should not overestimate the summer heat and a few days with temperatures above +35°C, as they are not a reason to switch to more viscous oil. The exception is if you live or spend a long time in coastal areas in summer, e.g., in Montenegro, when a possible switch from 5W-30 to 5W-40 of the same quality level is justified.

Deviations from the factory recommendation can be considered only in the following cases:

• Normal driving conditions: Lower W value for mountainous areas, primarily from 10W-40 to 5W-40, while for extremely low temperatures, 0W-40 instead of 5W-40 or 0W-30 instead of 5W-30 is suitable (5W-xx is sufficient for -25°C). For longer use (more than a few weeks) in high-temperature areas, switching from 0W-30 to 5W-30, or possibly from 5W-30 to 5W-40, especially for vehicles older than 5, and particularly 10 years.
• Short city trips: Similar to the previous case, but also for slightly higher minimum temperatures. Possible switch to 0W-xx at -20°C, and to 5W-xx already at -15°C. Increasing viscosity is not necessary even for temperatures up to +40°C (over +50°C in the sun).
• Long highway drives at high engine speeds: Heavy-duty conditions - switching to less viscous oils only when the true limit of W usage is exceeded, and with prolonged exposure to high temperatures (here already from +30°C).