I believe any oil is good enough, as long as it's the right grade. (Viscosity) for your intended working environment... I'm a diesel mechanic, and the latest truck engine technology (Volvo is my experience) is overhead cam and has four roller rockers per cylinder, has to have full synthetic oil with drain intervals up to 60,000k's So in my eyes synthetic oil is ok, (and before somebody jumps in and says diesel oil is different, current euro5 diesel oil is perfectly fine for petrol engines, and all euro5 diesel trucks have large $15000 catalytic converters which are very sensitive to the incorrect oils, ie. anything before euro5 And I have also seen many cam lobe failures on Volvo engines, and it always came back to bad case hardening, some warranty even paying for cams with over 400,000ks And back to the topic, I have a 08 turbo, and I'm freaking out about this, im nervous to remove my rocker cover