Oh....This is a bit worrying as she has had a Re-map, EGR blanked, De-catted....So will most probably need the proper stuff? I looked on the back of the Shell oil and it does say it is ok for diesels, but this 5-40 thing is of concern as it is that bit thicker. I suppose I could always try and sell the Shell oil on Ebay as it was over £40 when I bought it so may get some interest.....Or maybe put some Wynns oil treatment in as that is meant to drop the larger number?