Not much help, but I can say that my diesel doesn't make this noise.

Could it be the oil pump? (as it goes away when driving)

Maybe the oil is too light a weight? :dunno:

It's all a mystery at this stage. Easiest and cheapest investigative approach is to dump the oil, check for metal, cut the filter media apart, check for debris. Put new oil in, stuff that I know is correct (I have NFI what is in there now) and pray to baby jeebus.

Going to try do this tonight.....

I found the oil change very easy on this car, but make sure you have the right size tools.

Seem to recall the drain plug being 17mm, easy one but on a bit of an odd angle from memory.

The oil filter I am pretty sure on mine was a 32mm socket.
I tried multi-type of grips etc, but I had to buy the right size socket in the end, as it just wouldn't budge with anything else (Supercheap has them).
Super simple with the right size though!
Easiest and cleanest oil filter I have changed.

I use 5w-40 in mine, I think the manual also states 0w-30 can be used, but I feel it is just a bit thin.

Thanks mate. Yep, I got the 32mm socket....funnily enough, everywhere I read said it was a 36mm socket, so when I walked out of the store with my 36mm socket and tried a test fit in the car park.....I was at a bit of a loss. Took a bit of trial and error to work back to a 32mm!

I'm putting Motul 8100 X-Clean in it as it meets all the BMW requirements

Motul 8100 X-clean 5w40 - 1L | Clickable Automotive

I am in a Penrite phase at the moment, so used HPR5 5w-40 in mine, which is working well.
I'm sure the Motul will be equally up to the job.

As far as a flush goes, I have never tried anything.
I just drain and put in the new oil for my first change, and then change a bit sooner for the second change.
Then back to a normal interval for the next change.

Help - e53 Knocking from transmission - VIDEO
 

So I did a liquid moly engine flush, fully synthetic Motul oil 5w-40 change, filter and put in a liqui moly lifter additive. No change.

Tried unplugging each injector individually to see if I could isolate a cylinder. No change.

Only good news at this stage is there was no metal in the oil when I dumped it.

I think I'm going to have to bite the bullet and give it to BMW, if anyone can work it out, they can.

Only thing I can think it could be if it internal is the main crank pulley dampener, or something post torque converter.....it's just so rhythmic that it seems unlikely.

I did put an engine cleaner through mine. I waffled on if for a bit, but finally did it. Mine you dumped in and let idle for 10-15min then drain the oil. I also dropped the pan to check for plastic/metal and was relieved to find none. Other than the crap from the valve cover job the shop did sloppily..... :)

I would be ok with a flush, but not oil additives (like stop leak, etc.). Some of that stuff is like molasses and I could see it plugging up some of those small lubrication passages.

Hope its just an injector knock ;)

An update.

Shop did a balance test on the engine and found #6 cylinder out of spec.

Did a backflow test on the injectors and found 5 injectors were returning flow within spec but #6 way out. So #6 injector is shot.

Manifold came off and shop removed injectors and glow plugs for inspection. Found that #6 injector flange was broken, and injector was not sealing against the cylinder allowing compression to leak out.

Also needs CCV, Air filter, Fuel filter, EGR clean, glow plugs and glow plug controller replaced.....total of $3k. Some of this stuff I can do myself and had already purchased the parts pre-emptively - but the faulty injector is the bulk cost of the ordeal.

So my first week of X5 ownership has not done a lot to quiet the Break My Wallet stereotype! :-/

Assuming that the sound heard at the transmission area was just the piston slap echoing down through that chamber in the car - and being the rear most cylinder explained why it was better heard underneath than from the front of the car with the hood up.

Will keep you all posted.

Hi Mat,
As mentioned to you via PM on 5th,ideally you should connect car to Bmw diag and get them to check the injector readings,as the knock noise could be injector!!As you found out,sometimes you really need to hook up your car to BMW diag equipment ,as other diagnostic equipment fails to register problems,although INPA is pretty good.
Can you tell me what the injector 6 value was on diag?
If it wasnt sealing ,have they checked the washer / o-rings?
You have 2 different issues here !Out of spec and not sealing.Many times we got out of spec corrected by simply cleaning the injectors exits as they get blocked.