Aren't these boots filled with petroleum-based grease? If so, regular oil shouldn't hurt them a bit - if the rubber is designed to stand up to petroleum-based grease, then petroleum-based oil shouldn't hurt them either.

Now if the grease in them isn't petroleum-based, then that might be a different story...

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1984 300 Coupe TurboDiesel
Silver blue paint over navy blue interior
2nd owner & 2nd engine in an otherwise
99% original unmolested car
~210k miles on the clock

1986 Ford F250 4x4 Supercab
Charcoal & blue two tone paint over burgundy interior
Banks turbo, DRW, ZF-5 & SMF conversion
152k on the clock - actual mileage unknown

Not in half, just split it down one side.

For viewers who never had the pleasure of working on an old Audi...

The 100LS was front wheel drive, with the front brakes on the inboard [transmission] end of the drive shafts.

[this was fun for annual inspections, the inspector would usually take of one front wheel, pause for thought, take of the other front wheel and then ask me where the brakes were]

This required much larger / stronger driver shafts than would be normal on a car of its size. This in turn required a special press and a _big_ wrench to remove the axle from the front hub.

I originally thought the fix would only hold for a week or two - I didn't expect it to last a year.

I had an older 4X4 Isuzu Trooper, and did not have the desire nor the energy to remove the axles when a couple of circumferential tears separated two boots into "inner" and "outer" portions. So I "stitched" the two sides together, using a continuous stitch of stainless steel wire. I filled the insides with regular CV joint lubricant before making the final stitch or two. Then I cleaned the outside with grease-cutting solutions, carb spray. brake cleaner, etc. and thoroughly dried the outside where the stitches had been placed. Finally I put Goop (high strength stuff---much stronger than silicone) all around the stitches, making a loop right around the CV boot over the area of the repair. I intended to replace the boots or sell the car within a year or two, but ended up using it for a year, and then a friend took it over for the past three or four years. One of the repairs only needed one small touch-up after almost two years. No other zones of the same boots ever separated. If a highly-thinned Goop-like spray or liquid formulation were available, I suspect that most "aging" boots could be cleaned and then spray-coated or brushed with a few coats, and would last the life of the metal parts inside, unless some goof were to place a jack under one. I regularly use vinyl dip as an electrical insulator---but am unsure as to its strength, but some incredible flexible marine coatings are available---perhaps someone has a report on CV boot preservation using some similar preparation.

For those wondering or contemplating a cv boot replacement and have been putting it off due to lack of tools, today i replaced the inner and outer boots without removing the axles from the pumpkin. I also did not have to remove the differential mount. The axle left in place gave me the leverage to put the new boot on. The axles have enough play in them naturally to pop out of the splined mount on the wheel and when turned while removing will come out. You will need to have your car jacked up with the wheels at their full extension. Then disconnect you sway bar to work with the axle above the wheel. Make sure your car is properly braced because you will be pushing sideways on a jacked car and you do not want it topple over on you. You could remove the differential mount bolts for extra space, without removing the diff cover, but i did not need to.
Instead of yousing a flex astoria gun or 30.00 dollar tool, i went to autozone and purchased a 3.00 dollar long black funnel trimmed about an inch to fit the can on the axle. This worked very well when lubed with oil. I do not think i would use soap as it has properties that break down oil.
I also used the inner boots by dorman on both inner and outer joints as these went on very easy when lubed. The recommended outers were too tight and still had to be trimmed. The inner are a bit larger, and fit snuggly over the can for an air tight fit with the clamps. I used the supplied lube and added some more bearing grease to top it off. I did not remove all of the remaining oil in the joint as it will mix with the grease and bring the viscosity of the grease down. I dont think i would use oil considering the possible of the joint and that the grease will take up any slack.
My current joints have 288,000 miles on them and still seem intact with no scarring. I also replaced my boots as soon as they tore. I also have another vehicle to drive as some may not. I hope this helps, it took me about 3 hrs to do both sides not accounting for beer and cigar break.

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airedale2 Welcome to Texas
1984 MB 300D 266,000
1993 Nissan PU 271,000
2002 Tahoe 122,000
2004 VW TDI 75,000