As this engine is a diesel engine, Magnatec 10W40 is suitable for this vehicle, but a better product would be something that has specific diesel performance. so API CI4 plus performance would be ideal. Consequently a product such as castrol Tection Extra would be ideal.

this practice has been used for many years with little detrimental effect, in fact Cummins used to market a technology called the sentinel system that did exactly this. However with modern emissions legislation getting tighter and tighter then this practice is not really acceptable any more. Also with 2007 engines having exhaust aftertreatment fitted in the exhaust, this practice could actually cause damage.

There are 5 groups of oils which are used for the production of finished lubricants, these are known as base stocks. basically group I is a refined mineral oil, group II is a highly refined mineral oil group III is a partial synthetic oil, Group IV is a full synthetic mineral oil, and finally group V which is specialist oils. The cost of the base oil increases from group I to group IV, aswell as the performance, consequently group IV products tend only to be used when strictly necessary due to the increased cost (which can be 3 to 4 times that of a group I - but with the performance to meet.

VW 505.0 can be met with a partial synthetic product, sure you will get better performance from a full synthetic, but need to way up the cost benefits.