Generally all the mechanics recommend that the motor oil should be changed every 5 000 km. The automotive manufacturers recommend that the motor oil should be changed starting with 10 000 km mentioning “normal service”. For “severe service” they recommend 5 000 km. What means “severe service”?
– frequently short distance trips (under 7-8 km);
– heavy traffic trips (stop and go city traffic);
– trailer towing;
– driving in dusty conditions;
– driving in cold weather;

If you read the vehicle’s users guide you can find two types of driving conditions: normal service and severe service. Normal service means that the vehicles are driven under ideal circumstances. Unfortunately most of the cases are severe service driving and here are some examples:

Engine cold start– After ignition the engine needs a certain amount of time to reach optimum functioning parameters. During this time, the fuel is not burning entirely causing appearance of fuel residues. Dilution with unburned fuel residues is the most important oil contamination source.

Short distance trips– Your car’s engine works best on long trips made at a constant speed. Unfortunately, most of us perform short trips and quick. The city or repeated cycles of start-stops are extremely harmful for the engine and oil.

A loaded car– It is good to know that additional options installed on each vehicle comes with an additional surcharge for the engine, resulting in higher operating temperatures. Automatic gearbox, climate and air conditioning, each comes with an additional 10 to 15º C to the engine temperature, thereby subjecting it to further efforts to cool down.

Car driven occasionally– Cars left unused for longer periods are at risk of engine corrosion and rust, caused by the condensation developed inside the engine.

Towing– Towing a boat, campers, trailers, etc. requires extra work raising engine’s operation temperature. Engine’s operating high temperatures requires more oil to cool the engine.

Dusty conditions / bad roads (dirt)– In terms of dusty conditions, tiny particles of dust and dirt get into the engine. The air filters are not capable of producing perfect filtration; there will always be fine particles that will escape through the filter, developing a suspension in the oil, which will lead to premature engine wear. Each one of us are meeting these conditions every summer, on dirt roads or on roads that are under repair / maintenance.

The conditions listed above define the so-called “harsh environment”. A recent American study revealed that more than 90% of trips are taking place in severe conditions