Performance of engine has been ever increasing and must often withstand long motorway journeys or long idling times. All of these difficult conditions can lead to high engine temperatures and increased levels of burned and unburned fuel contaminants that build up in the oil.  

Recently, engines have been getting smaller and the demands on their performance have been increasing. That is why Castrol places great emphasis on complex full synthetic oils to cope with higher engine pressures and be efficient in terms of fuel efficiency.