Obvious from the title that i went and put unleaded into my TD4. It happened saturday. Got distracted and put about 20 litres of the the wrong stuff on top of about 8 litres of the right stuff. Didn't realise at the time and drove about 7 miles to the supermarket. With a few miles to go it started to get a bit jumpy and that when i thought i might have done the dirty deed, but i wasn't sure then. Did my shopping, went to start her up and she rearly struggled to start. She started but she was far of happy so i pulled into the supermarket garage and switched off. As i didn't get a receipt for the fuel i rang the garage and they confirmed that i actually had been an idiot!
Rang up the fuel doctor, and a very nice chap called clive turned up and sorted it all out for me. Drained the tank, put in some good stuff and off i went! Went to go out the next day, drove about 3 miles, oil light came on and she died on me. Managed to pull off the main road, tired to start her again but she wouldn't. Left it about 10 mins and she started! So i turned round and headed back to the garage to put me diesel in. I guess i thought there may have been some unleaded still knocking about and i thought some more diesel might dilute what was left in there. Thing is though now the engine is making a lovely tapping sound in time with the revs. I feel i may have done something really expensively bad to the engine. Also on the way to work this morning the oil light kept coming on and going off again. I don't know if this is separate to the wrong fuel thing and I've just run it dry of oil or summint. On a separate note i have 7 litres of oil turning up to day so i can do a service at the weekend! Anyways, apologies for the convoluted message, just wanted to share my idiocy and maybe some of you guys may have some thoughts on the issue.

oooppps.
As I'm sure you are aware, this can cause some very serious damage.
Fuel pumps are usually the first to go as they need diesel for lubrication and equally petrol is a solvent.
Re oil light, I can only think that petrol has found it's way to the sump. Your oil change will hopefully solve that issue.
There isn't much more you can do. Only time will tell.

Thanks Mr Kent. Hopefully an oil change will solve that issue. Just worried about the tapping noise thats appeared. Sounds like a lawnmower at the moment!

Have you checked you oil level? I mean physically with the dipstick?

you can put a gallon of petrol in with a tank of diesel and it will not do any harm if fact in the old days before additives to stop the diesel freezing that's what we used to use but get the ratio wrong and your engine will suffer.

In your situation the tank and fuel system should have been drained. Given that you drove for 7 miles on virtually pure petrol will have confused the sensors and therein the ECU no end.
Get it plugged into a DX and that may give you a better idea.

The oil turned up at wörk today so it now has the right amount in it, as it was way down on oil as it turns out. But I think the damage has been done. The tapping is coming from the left of the engine. I cant help but think that maybe something is fouling somewhere in that area, but I don't know, im no expert. Ive got some time off tomorrow to take it to a garage and get it looked at. Thanks for your input guys.

Could be a Valve knackered due to lowered flash point and pre ignition, sounds like it's a Head off job for a start.

Took it into a LR specialist this morning. They took the injectors off one by one but the knocking didnt stop. But on the No.1 injector it was quieter so they reckon the issue is deeper unfortunately. Maybe a seal, i dont know but they are going to diagnose tomorrow afternoon. Its sounding expensive.

Just got off the phone from the LR people. Apparently its blown a piston! And they've given me a ballpark figure of around £1000 to fix it!! To say i'm a little bit peeved is an understatement. Really annoyed at myself for being such a doofus.
Anyone else had a piston replacement and did it cost a lot?
As you can imagine im really interested in prices!

a blown piston? if you are having it done ask for the od parts back to remind you and then you can really see what it has done and you should take it to another garage LR garages charge top whack.

Could also be a problem with the HP fuel pump...if so, maybe you might consider just changing the complete engine.I think that would be more economical than paying a fortune in labour & parts due to the amount of dismantling, cleaning, checking etc. involved. You should be able to get a full engine with a warranty from a reputable breaker. The Beemer engine is pretty bullet proof providing it has been looked after and a good breaker will have run it before pulling it out or maybe you could hear it running.

I wouldnt be ****ing about changing a single piston. Besides, who knows what other damage may be done and where the swarf might have ended up. It would be a real bummer to cough a grand for this and for the HP pump to die in a few weeks time due to running unlubricated..
I would be on the look out for a good replacement second hand engine.

A £1000 sounds about right anywhere you go.
I agree, another engine for sure.

piston change on a td4 is no great difficulty about £70 for a new one , id be more interested in hp pump

I've seen the coating come off the high pressure pump. It was so fine it went thru the filter and got every where. The inside of the fuel tank sparkled. Every part of the fuel system had to be replaced at huge cost just from misfueling. Also seen a high pressure pump seize and shear the drive off. Depressing!