Man D2848 LE403 oil levels

If the mfg manual does not direct an exact method, Please consider this;

Read cold in the morning. All of the oil has drained from the galleys and filters.
This will be on your full mark.

Rite after you shutdown the engine,
15 minutes after you shut down the engine,
3 hours after you shut down the engine, will all read different. There is just so much to drain back into the sump.

Also, let your dip sit in place a few seconds before pulling it back out to read.
Cold in the morning, just pull the dip and read it.

If you must read the dip on a hot or warm engine, have the oil level set full when cold, then run the engine.
Find a consistent time to check your warm engine, ie 10 minutes after shut down, then read your dips, should read low but in range.
Remember that level.
Always read your warm engine at that same time delay. 10 minutes later, it will change.

Same for your clutches.
Adjust levels to the full mark per mfg's instructions (running in neutral, rite after shut down or cold)
If your clutch level did require running in neutral or rite after shut down, when cold the next morning, pull the clutch dip and scratch that full-cold level on the dip.

Why pull them out, then wipe them, put them back in, wait and pull again?
If there cold, The level is on the dip..
AND, no oil in the dip tube? Perfect read.

Since you asked for "any" advise, here's mine, with the premise that I wouldn't blame you for laughing at it.
But is's based on 6 years of ownership of a boat powered with the very same engines as yours, and countless chats with several different MAN engineers.

And the advise is, particularly if you like to get (as I always did, up to these engines) repeatable and consistent results from the dipsticks readings: forget it.
MAN engines (not just ours, btw) are well known for being a bit unpredictable in the time it takes oil to drain completely, depending on God knows what.
In this respect, Capt Ralph nailed it when he said that readings can be very different, and I can only add that those differences are not even constant.
I mean, two readings, both taken exactly 3 hours after engines shutdown may well give different results depending on external temperature, boat load distribution, and even whether the boat is in a somewhat bumpy anchorage or docked and 100% steady - go figure.

Besides, those min/max marks which you have on your dipsticks do NOT come from the manufacturer, who doesn't know whether the engines will be installed horizontal or at any angle (either rear or fwd, depending on whether the boat has straight shafts or v-drives).
So, they delegate the placement of those marks to their MAN dealer who assisted the builder in the installation and attended the first sea trial.
And this chap should fill the engines with the min quantity of oil (20 litres, if your boat has the standard sump as mine), run and warm them up, wait till they cool down and drain, and place the "min" mark.
Done that, he should put other 4 litres of oil, do all that again, and place the "max" mark.
So, depending on how accurate this guy was, even the dipstick marks could be not 100% trustworthy.

In fact, right after purchasing the boat, I faced exactly the same problem that you mentioned, and I was puzzled enough that upon the first oil change I made a full re-check of the dipstick marks with my mechanic, starting from the right oil quantity rather than the marks, which in fact eventually we adjusted a bit.
I'm not talking of night and day differences of course, but still meaningful.
And I'm sure that if I'd do that again, the level would never hit those marks perfectly - neither the originals, nor the newly checked ones.

Now, the good news is that these engines burn very close to no oil - unless overfilled, which is somewhat more likely than starving them. So, during my routine checks, nowadays I don't even bother looking for a potential consumption trend or for consistency between engines, as long as the level isn't drastically wrong - which I never experienced so far, fingers crossed!
What I'm more careful about is "feeling" and smelling the oil, which should neither show signs of emulsification, nor be burnt.
And the other thing I try to check is how much oil comes out upon oil change, which should always be at least 20 litres but never more than 24.
Other than that, I don't mind finding one dipstick a bit higher than the other, since I know that the next time it could well be the other way round!

+1 to all that.
Having said all what I just said, my preferred way to check oil is before rather than after running the boat.
Which can mean anywhere from 10/12 hours (with the engines not yet stone cold, but almost), or weeks later (stone cold), depending on how much the boat is being used during the season.
Anyhow, in those conditions, I just pull the dip and check the oil, job done.
In my experience, checking after 45 mins as the OP mentioned is akin to toss a coin.

I've witnessed when you put the dip in to quick and back out.
The air from the rubber top stop pushes the air down the dip tube. Hence giving a while before pulling the dip back out.
Never had a level issue on pulling a dip, cold, first pull in the morning.

Oh Well, We present our trials and experiences for the OP (Original Poster, butch w) to reason and take advantage of.

You said they are V10 engines - out od idle curiosity, 820, 1050 or 1100?

I meant to mention this, but I forgot - just as another small reminder for the OP:
Beware, it's not only the angle but also the length of the tubes which is different.
In fact, for obvious convenience reasons, they are both placed in between the engines, and therefore on different sides of them.
The longer stick goes on stbd engine and the shorter on port engine, or the other way round if the boat is on v-drives.
But both fit either tubes, if by accident you swap them.
So, be careful, because that can give awfully wrong readings!

In a boat??

I am familiar with that manual, because your D2840 LE401 engines belong to the same family of my (and Butch's) D2848 LE403, and the operation manual is the same.
Now, you are correct in saying that it suggests to check not long after shutdown (20 mins actually, not 10 - but that doesn't make a relevant difference).
I am attaching an abstract to the relevant page, together with the covers. Is this the same document you are referring to?

Anyway, the general consensus among several MAN engineers I spoke with is that those 20 mins should be regarded as an "at least" amount of time.
And all of them recommend to let the engine cool down and drain for much longer.
That said, I appreciate that if your method works well for you, there's no reason to change.
And I fully agree with your last statement anyhow!

If like me you appreciate having as much boat documentation as possible at your fingertips in electronic format, just ask.
No problem to send you the PDF file of the whole manual from which I extracted the page above.
Just PM me a mailbox address, because it exceeds the max forum size.
BTW, depending on how much you fancy DIY, you might find also the parts list and the repair manual of some interest.

"Below the upper notch..."
What do you read in the morning cold without running them first?

I'm sure consistency would be the best practice. But who wants to go check hot engine dips?