Hybrid vehicles – e-drive coupled with combustion engine
Hybrid vehicles are propelled with the help of an e-drive, whose battery is recharged where required by a combustion engine, usually running on petrol. This allows the engine to almost always be operated at approx. 2,500 revolutions in the optimum efficiency range of over 35%, while in conventional operation, no more than 20% is achieved. Traditional engine oils were originally used in these engine designs.
Special oils are now increasingly used for hybrid engines. As hybrid engines usually run in a relatively narrow speed range and are subject to the same strain, oils with lower viscosity classes SAE 0W8 to 0W20 are used.
With the help of the battery, the oil is preheated in such a way that there is almost no cold start. Yet in a frequent interval operation such as in urban traffic and operation at a nearly constant speed, these engine oils change in different ways to their classic equivalents. However, there are as yet no results from longterm tests with these engine oils from hybrid vehicles.
That is why regular monitoring of the engine oil to determine the optimum oil change interval combined with an assessment of the systems' durability is definitely recommended.