A new oil level glass assembly came with my bike purchase.
I'd like to install it as the existing glass is cloudy.
Can this job be done without dismantling anything else?

Yes.

Another option, it could be the inner face of the sight glass and the silver backing plate behind it that are dirty, which was an issue on one of my bricks. Next time you change the oil filter you can get access to clean it with a brush.

I will try that, thanks.

It's really not easy to access the inner glass, as there's a metal sheet behind.
It's much easier to change it.

My method:
1: Break the glass.
2: use a large screwdriver or anything that you can use as a lever to remove the window;
3: press the new window with a socket of the same diameter.

Yes, I hear you screaming: "What about the glass particles in my engine?"
That's why there's an oil filter which allow no glass particles to pass.
Furthermore, I usually change the window before flushing the oil.

I'm going to be changing mine in the upcoming weeks as it has a very slight weep at the bottom. I've seen videos online where the owner has used a soldering iron to melt a hole in the plastic and then stuck a screwdriver in the hole and levered it out. Another fellow on the BMW MOA  Facebook page heated up a screw and then threaded that in, let it cool, and pulled it out (I think) with a pair of pliers.

I'm endorsing jbt's wham/bam replacement method. It's chock-full of transient delight.

Laitch wrote:I'm endorsing jbt's wham/bam replacement method. It's chock-full of transient delight.

2: Crowbar.
3: Sledgehammer.

The glass inside makes it seem a bit different to a traditional oil seal, and I s'pose it is in a way. But it is just an oil seal at the end of the day. Get that glass out of the way in a method of your preference, or on the advice of previous posters. If you're a tool collector like me, and think you might use it more than once in a year, obtain one of these. They make it swift, tidy and easy to pull a seal. Mechanical advantage is everything.

Blast! - a tool I don't have.
But I will make something like it.
Who am I kidding? I'll just buy one.

Job done.
Someone suggested using a length of half inch wooden dowel through the oil filter access hole, to hammer out the old glass.
I did that, it came out easily. It is intact, with barely a small dent on the metal back plate.
New one went in almost as easily, smeared with oil and tapped in with a socket on a short extension.
I was puzzled by a wire circlip packaged with the new glass, but found out it isn't used on my particular engine.

The reason for cloudiness of the old glass is dark oil deposits. I think I'll keep it as a spare, if I can get it clean.
I read in an old message here the suggestion to do a couple of oil changes with a diesel oil.
I guess that's to take advantage of the higher amount of detergent, to clean engine internals.
I'm used to doing this in my old Ducatis. It's an accepted method amongst bevel bike owners to do that as a way to prevent sludge build up in the crankshaft's centrifugal filter.
There is no other filter in the early versions of those engines.

Jordan53 wrote:Blast! - a tool I don't have.
But I will make something like it.
Who am I kidding? I'll just buy one.

I promise you: the first time you use it to pull a seal you'll pull way too hard, the seal will fly out and it will be weeks before you find it DAMHIK.

Looks like it will make a perfect back-scratcher too.