Now, before I get castigated, the oil I put in was only meant to be in there for a couple of thousand Kms so I wasn't too too bothered what it was, so long as it had a name I knew (forgotten it now, sorry) and the right specs and had the word "diesel" written on it.
Brief recap: after service noise appears. You can only hear it in the car, with your foot down between about 1500 and 3000 rpm, when it fades and vanishes in the cacofony. It doesn't do it hot. Or if you drive it like grandma (how I have to drive with the other half

So, I went back to the bottle to see what'd done and I noticed the word "synthetic" doesn't appear anywhere. Oh. Ok, I'll change the oil for one that does. Go to the shop where my other half explains why I want synthetic, whereupon the guy explains to me that I absolutely must not put mineral oil in an HDI and have probably done loads of damage to the tappets and maybe even burned a valve or two.
Is this bollocks, or have I goosed my new mota????? I can't find anything about it on the 'net.
Anyway, with the new supa-dupa fully synthetic oil, the noise is less but still there. Tommorow it's being left at Pug for a few hours to cool off, then I'm going to try to scare the mechanic again. Then I'll know if it's head in the oven time...