I have never understood the use of baby oil as a cleaner because it will not rinse out. I think the only reason it is used is to soften hard smegma and because it is generally non-irritating. That being said, I have used Excalibur and didn't much care for its texture. It is very "chunky" and doesn't seem to suds much at all. It will work, but I think you end up wasting more than necessary. I have switched to eZall sheath cleaner & like it much better. I don't agree with cleaning them only once or twice a year, but then again, I don't agree with the thought that you shouldn't bathe your horses too much. Even if the sheath isn't that dirty, it is a training issue and a part of the grooming process. I have also heard (and agree based on my own experience) that horses with large amounts of white hair with pink skin underneath require more sheath cleaning than those with dark pigmented skin.
The technique is what is most important to getting a clean sheath. This is what I do:
Warm water is a must. To prepare, you tear several chunks of rolled cotton into approximately 3x3 inch squares or balls and put them in a bucket. I usually do 10-20 depending on the dirtyness of the sheath. Mine aren't too bad because they are cleaned very often. Alternatively you can use paper towel pieces, but they don't have the "grab" that cotton does.
Fill the bucket with about 3gal of quite warm (100-105 degree) water and some of the cleanser then swish it all around a bit. Put a glove on whichever hand you wish to touch the sheath with. This hand will NOT go in the bucket. You will use your ungloved hand to pass cotton to the gloved hand and to run the hose.
Now if your horse is extra gross, it would be a good idea to put some cleaner on your glove-hand and smush it around up in there letting it sit for a while. Then you can pull out as much gunk as you can before you have to use the cotton to scrub & wipe the skin. Use the hose to rinse your gloved hand as needed and to rinse the sheath out a few times during the process.
When you get to the cotton, pass it to the gloved hand, use the ungloved hand to squirt some cleaner on it and go to town scrubbing every direction you can. For the first cleaning, it is more than adequate to only get the folds inside his prepuce (basically the first portion of the sheath located below the abdominal wall) In order to get his penis clean, you may have to go elbow deep. You will probably find dryer bits of stuff past the "ring" that separates the external area from the internal area. This is where you will have to just feel around until you find the pouch above the urethra.
Unless of course you have a wonderful horse who drops for the whole process! I have a couple that *enjoy* it a little too much, one that constantly holds his leg up like a dog & gives me the death stare and the rest (including my stud, oddly enough) are very shy.