I used to own a Volkswagen TDI that required the 507.00 spec oils… Most if not all of them were heavy 30 weight oils and their low temperature cranking were on the higher end as I often thought of the 507 oils as a heavy robust 10w30/40 oil that gave up low temperature performance for lower volatility-original Mobil 1 5w30 esp had noack of 5.4, excellent high temperature stability-most had excellent high flashpoint numbers, and higher viscosities for thirty weight oils to give the Diesel engine similar protection that traditional forty weight oils gave, but relatively lighter viscosity also gave better fuel economy compared with a forty weight oil.