Back in 2005, Agip introduced their Longlife III 504/507 oil, of which they wrote (in somewhat broken English)...

Product information - Agip 7008 - PDF file (74 KB)

The special Longlife III quality of Agip 7008 can be clarified with the following 5 criteria:

1. At the performance the Longlife III quality can be equated with the Longlife II quality. Thus also the new quality for the prolonged oil-change intervals (WIV) is permitted for vehicles with the classification QG1 on the data carrier. The performance meets a level according to ACEA A3/B4.

2. The fuel saving also has to be proven in the engine test and has to show at least the same dimensions as Longlife II oils.

3. Mid-SAPS oils contain a special additive package with a reduced content of ash forming components. Fewer particles are formed at the combustion which ensures a long operating life of the DPF.

4. The SAE 5W-30 is necessary for diesel vehicles with diesel particle filter (DPF), since the soot in the DPF has to be burned at certain intervals.
This is made possible by an increased amount of fuel injection. However through this also a clear engine oil thinning can appear which could lead to a critical area of the engine lubrication at a SAE 0W-30. The 5W viscosity takes care of the necessary safety of the engine lubrication.

5. Highest requirements on the cleanliness of the inlet valves of the FSI engines (direct injecting gasoline engine).
Since there is no more contact of the additivated fuel with the inlet valve, the partially oil conditioned deposits cannot be reduced over its cleaning ability anymore.
So it's not just a matter using a low or mid-SAPS oil - how the oil is formulated also needs to be taken into consideration.