The petrol engine and post-treatment system components that use them (such as three-way catalytic converters) are given long-term protection.
The 10W-30 grades reduce internal friction within the engine so it can deliver full power, while at the same time generating fuel savings.
Protection for pollution-control systems: their low phosphorus content prevents the 3-way catalytic filter from getting clogged up with soot. Reduces emissions of NOx, HC and CO in particular.