My '82 300D had about 210 ml of oil in each of the three joints that had not leaked.

I flushed them with brake cleaner and refilled with 80W90 hypoid gear oil. Given that the axles are on the rear and fairly low angle, I didn't feel all that good about using grease. Even Redline specified that their grease was intended for high angle CV joints.

There are a number of different CV joint designs in existance. Some axles even call for different grease for the inner versus outer joints. Bottom line is that what is good for one design isn't necessarily good for another. My joints looked incredibly good considering their age. I decided not to argue with an obviously successful strategy and replaced oil with oil.

Front Wheel Drives where the Transaxle and the Engine are both subject to similar heat as the Engine. They also make Silicon Boots for the inners on front wheel drives.

Just my experience: When I first bought my Car I found the Axle Boots Cracking but not leaking. I was also new to this forum and had no idea of re-booting.
Anyway I bought a set of Cardone rebuilt axles.

After 5 years I had no problems with Axles except that it looked as if the stock type boots were cracking. When I removed the old Axle Boots all joints of the axles were filled with grease.

In the pic you are looking at the old grease that was in the Axle. Note that the Axle and Boot are nearly entirly filled with Grease.

When I re-booted I made sure I used enough Grease to duplicate the amount that filled it up. A single grease packet may is likely not enough.

I looked for an could not find any specific grease called up by MB on WIS. Out of interest, where did you find those inner/outer greases specified?

To clarify, that comment was global in nature, not MB specific. Some Asian vehicle axles feature totally different joint designs for the inner and outer joints and specify different lubrication.

The W123 inner and outer joints are of identical double offset design. There would be no reason to use different lube for the inner/outer joints.

What's the general consensus on using a split boot?

Have had to replace a rear axle after a boot cracked open on a road trip.

Noticed some cracking on the other and wouldn't mind a preemptive solution (one that doesn't involve 3-4 hours of paid labor)

There has only been 2 people that claim to have used them. However, there is a part number listed in one of the threads in the repair links. I am at the Library and do not have access to my notes to post that.

I think the one guy said he sold the care a month or so after installing the split boot (or I read that over on Benzworld) so there is no history there.
With a split boot you need to uses Grease.

If the cracking is slight you might experiment and get both rear Wheels off of the Ground and degrease the boots good and let it dry. After put it in gear (be sure the front wheels are blocked) so the axles turn and spay the rubber with that spray flexible rubber sealant they advertise on TV.

The experiment is to see if that does the job and it lasts a reasonable amount of time.

The TV sealant is called Flex Seal. But, there is other makes of it.

There is a split boot part number in this thread. Post #6
http://www.peachparts.com/shopforum/diesel-discussion/385572-small-hole-axle-boot.html

Don't use that stuff! If you want to use anything, use a Polyurethane. And after cleaning boots thoroughly by brushing with fine wire brush then acetone. Possible products are 3M 5200 or Sikaflex 291 (which is much less expensive).

Not a solution though, especially for the already broken boot. Split boots properly installed should be OK, but getting proper bonding while working under car is the challenge!

I should have clarified -no leaking yet, just cracking old rubber. The boot is still totally packed with grease. In theory, reinforcing those cracks is probably a good move.

Is the 3m product a spray?

The spray with the axle turing the spray could go on more evenly.

The 5200 and the 291 are quite thick paste like adhesive-sealants. I used a glue type brush and painted the 5200 on. Made sure I first got it into the cracks. Just rotated wheel by hand about 1/8 of a turn at a time and painted on the stretched side of the bellows, not the collapsed side. Used a good light so I could see what I was doing. Although the 5200 didn't run, I still rotated the wheels about once per hr during the initial cure time to even out any tendency to flow. They do have a quick cure version.

Those spray on products are not adhesives and are quite thin - more paint-like. I wanted something that would adhere strongly to the rubber (which I spent some time cleaning and abraiding). Polyurethanes are very good adhesives.

But really, I don't think coating boots is anything more than a Q&D temporary fix. If the actual boot splits, a thin coating of rubber like sealant of any type is going to split too.

I just finished my axle reboot job. Except that I have to give the RTV 24 hours to cure before I can refill the differential. Overall, it was a fairly straight forward job. I was concerned that removing the axles might prove to be a challenge, but when fully compressed I had about a millimeter to spare. That was with the differential fully jacked up. Also replaced the differential output seals.

The Astoria tool was quite the impressive device. I used the Astoria 3001 boot. For sure, the boot is not as thick or strong as the genuine part, but I suppose that compromise is necessary when asking a one-inch diameter hole to stretch to four times that size.

I took photos of this job when I re booted both axl s on my 300CD but I cannot get the computer to find the dang photos in my iPhone 6s......

I have joined iTunes and still have NO IDEA how to download the ding dang photos .

Can you send the Photos attached to an eMail to a regular computer?