It's true we have a massive amount of diesel cars driving around in Europe. BUT, please don't copy this in the States!!! All diesels, even the less polluting ones (I don't use the word 'most environmental friendly) cough out dust particles that you don't find in petrol cars exhausts gasses. The most recent ones even the thinnest particles. And they are the most dangerous for our longues. I refuse to drive around in a diesel car for that reason. We have never seen such an increase in longue deseases in Belgium and other 'economic well developed areas' as the last decades. And it's a proven fact that diesel engines highly contribute to this problem.
There are some diesel cars in the US (most VW models available with TDI, for example), but most companies aren't willing to spend their R&D money on the systems required to meet emissions requirements. Sure, they'd be willing if people were willing to pay more, but people are not.
Going back to what got us on the subject of diesels: AFAIK, diesels have more severe oil needs.
Just filled up again, and the result is still very positive.
For the first time my wife drove this car because we sold hers (the Peugeot: Frenchy). Her car will be changed for another Civic i-DSI (exactely the same as mine but in orange) next week, so she used mine last week. This info is important because my wife does not drive economical at all and she drives only very short distances (1 to 2 miles).
And even under these circumstances the mpg is far above what it used to be with the previous oil (almost 44 mpg compared to approx. 40 mpg, see gaslog).
I also did some investigation and know now for 99% sure the previous oil was 10W40.